SUSTAINABILITY OF PATENT-BASED … of Patent-based Competitive Advantage 3 Sustainability of...
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Sustainability of Patent-based Competitive Advantage 1
SUSTAINABILITY OF PATENT-BASED COMPETITIVE ADVANTAGE
by
Kathryn Rudie Harrigan
Henry R. Kravis Professor of Business Leadership
Columbia University, 701 Uris Hall, New York, NY 10027 USA, 001-212-854-3494,
[email protected] [corresponding author]
Maria Chiara DiGuardo
Associate Professor
University of Cagliari, Viale Fra Ignazio 74 – 09123, Cagliari, Italy, 039- 0706753360, [email protected]
Research assistance was provided by Jesse Garrett, Donggi Ahn, Hongyu Chen, Elona Marku-Gjoka, the Patent Office of the Sardegna Ricerche Scientific Park and Thomson Reuters.
Sustainability of Patent-based Competitive Advantage 2
Sustainability of Patent-based Competitive Advantage
Abstract
Patents have been touted as being the type of resource which provides a basis for longer-lived
competitive advantage, but as the pace of technological change accelerates, even patents have
become questionable sources of sustainable competitive advantage. In settings where no
sources of competitive advantage are sustainable for long (and no resources convey advantage
forever), managers have sought temporary respite in resources, in how managers organize and
coordinate their operating activities and routines, in recruiting superior knowledge workers,
developing keener learning capabilities and absorptive capacity, and in learning how to copy
competitors’ sources of competitive advantage more nimbly. We find that the duration of pa-
tent-based sources of competitive advantage is limited, but that duration is longer where firms
have patented inventions that incorporate a broader range of technological knowledge that is
not core to the grants described in their respective patent applications.
Sustainability of Patent-based Competitive Advantage 3
Sustainability of Patent-based Competitive Advantage Introduction
Competition is like being on a treadmill (also likened to the Red Queen effect) in the sense that
firms must continually renew themselves through various types of innovative activities in order
to keep up with other firms’ newest competitive sorties (D’Aveni, 1994; Teece, et al., 1997). The
unique and inimitable resources and capabilities which give the incumbent firm temporary pro-
tection from losing customers’ patronage are the basis of that firm’s competitive advantage
and the duration of its protected status from rivals’ imitation refers to the sustainability of said
advantage.
Imitation is the most likely means for competitors to try to steal away customers; new
entrants may even be successful at doing so unless the incumbent firm possesses some basis
for serving customers that is especially difficult for competitors to emulate (Bain, 1956; Peteraf,
1993; Porter, 1980; Wernerfeldt, 1995). As an industry’s structure evolves, competition therein
becomes a fight against the eternal price-cost squeeze of cutthroat rivalry and diminished
product differentiation which destroys firms’ distinctiveness (Porter, 1980; 1991). As firms
push back against the profit-eroding forces of competition, they seek to acquire (or develop)
new sources of competitive advantage that will either preserve customers’ willingness to pay or
improve firms’ abilities to take expenses out of their internal cost structures. In this process,
firms’ competitive struggles seem, at best, to provide only temporary respite against incursions
by increasingly-aggressive adversaries who can recombine their innovative resources and ideas
creatively to win the patronage of customers whose loyalty is fickle (Bettis and Hitt, 1995;
D’Aveni, et al., 2010).
Sustainability of Patent-based Competitive Advantage 4
As their industries trudge inexorably towards competitive stalemate, managers inside
these beleaguered firms hunt for some temporary respite against creative destruction (Schum-
peter, 1942) and disruptive competitive changes (Christensen, 1997). Their basis for serving
customers effectively evolves continually from gaining advantages that may reside in resources
(Bain, 1956; Barney, 1991; Dierickx and Kool, 1989; Peteraf, 1993; Thomas, 1996; Wernerfeldt,
1995) to finding advantages in how managers organize and coordinate their operating activities
and routines (Porter, 1996; Powell and DentMicallif, 1997) to advantages based on recruiting
superior knowledge workers (Drucker, 1999; Groysberg, et al., 2008; Harrigan and Dalmia,
1991) to developing keener learning capabilities and absorptive capacity (Arikan and McGahan,
2010; Cohen and Levinthal, 1990; Lane and Lubatkin, 1998; Lane, et al., 2006; Volberda, et al.,
2010) to making the firm’s organizational capabilities suitably dynamic so that its people can
copy competitors’ sources of competitive advantage more nimbly (Helfat and Peteraf, 2003)
because the duration of any single basis for competitive advantage seems to be brief. In many
industries, it seems that no sources of competitive advantage are sustainable for long and no
resources convey advantage forever (Collis, 1994; D’Aveni, et al., 2010; McGrath, 2013; Ruefli
and Wiggins, 2003).
Patents have been touted as being the type of resource which provides a basis for long-
er-lived competitive advantage (Reitzig, 2004; Sander and Block, 2011; Schankerman, 1998).
This hopeful outlook has endured, perhaps, because patents have granted a temporary mo-
nopoly on a particular use of knowledge as it was combined in firms’ useful inventions. As the
pace of technological change has accelerated, however, even patents have become questiona-
ble sources of sustainable competitive advantage. Our contribution to the debate concerning
Sustainability of Patent-based Competitive Advantage 5
the duration of competitive advantage investigates whether patent-based advantages prove to
be the exception to a scenario where most investments in resources and capabilities offer di-
minishing returns. To do so, we contrast the operating profit margins of firms having patents
with those who do not, as well as test propositions concerning which types of patents offer
longer-duration competitive advantages. In order to investigate the duration of patent-based
competitive advantages, we also decompose the components of patent applications to distin-
guish which types of patents are most-difficult for competitors to emulate.
Theory and Hypotheses
Competitive advantage arises from the temporary amassing of resources and capabilities which
allow vendors to win customer patronage while also earning normal profits (or better). In 1994,
Collis posited a scenario in which entry barriers would become meaningless and the value of
resources, capabilities, organizational routines and other activities that had previously been
considered to be sources of advantage would be easily matched by substitute assets of equal
value. Tacit knowledge would no longer create relevant advantages in this scenario as competi-
tors learned that they need not copy the extant sources of firms’ advantage; they needed only
to imitate those product traits which customers valued as quickly as they were introduced by
their innovators. In such a world, Collis (1994) noted, there would be no sustainable competi-
tive advantage if competitors could quickly match any product-market proposition that cus-
tomers found valuable.
Collis’ (1994) scenario became plausible because many scholars found that superior per-
formers had difficulty in sustaining their performance levels over time if their distinctive value
proposition was easily imitated by rivals (D’Aveni, 1994; McGrath, 2001; Ruefli and Wiggins,
Sustainability of Patent-based Competitive Advantage 6
2003). In 2010, D’Aveni, et al. posited that Collis (1994)’s scenario of an environment with no
sustainable advantage represented a special case of industry structure―anticipating, as McGa-
han and Porter (1999) had concluded, that adverse changes within an industry’s structure
would have a more persistent negative impact on firm profitability than would changes in firms’
individual strategic outlays. Firms continued to invest in patentable inventions in the hope of
earning more-than-proportional returns for making R&D investments.
Not only have firms continued to invest in strategic resources (such as advertising and
R&D) without causal certainty that such activities would increase sales and profitability, firms
have also continued to modify their organizational routines in order to renew their competitive
capabilities in an effort to stay abreast of competitors (Barney, 1986; Novak and Stern, 2008;
2009; Nelson and Winter, 1982). Most firms have been oblivious to the risk that the value of
patents as a source of competitive advantage could become less enduring when the type of in-
novation needed to cope with competitive turmoil became more radical in nature or when their
scientific knowledge grew obsolete (Henderson, 1993). The durability of patent-based ad-
vantage, in particular, was at risk of becoming shorter-lived within industries that were charac-
terized by rapid and multi-faceted technological change (Tushman and Anderson, 1986).
Patent-based advantage
Technological innovations (such as patents) were thought to be a source of differentiation that
offered a more-enduring competitive advantage because some inventions’ attributes were truly
inimitable; although technological progress occurred often, the evolution of industry structure
fostered spurts of innovative activity (punctuated by disruptive years of discontinuous change)
and awarded temporary entry barriers to the victors in the form of patent-based competitive
Sustainability of Patent-based Competitive Advantage 7
advantage (Aghion, et al, 2005; Cohen and Levin, 1989; Kamien and Schwartz, 1974; Scherer,
1967; Schumpeter, 1942; Tirole, 1988).
Because high-quality patents earned rents through their royalties, the stock market val-
ued firms who had patents as though their patents were indeed valuable (Bessen, 2008; Bos-
worth and Rogers, 2001; Cockburn and Griliches, 1988; Griliches, 1981; Hall, et al., 2005; Lan-
jouw, 1998; McGahan and Silverman, 2006; Villalonga, 2004), even though only a small propor-
tion of all patents actually captured large returns from their royalties (as was indicated by the
proportion of forward citations that they garnered) and those inventions were constantly at risk
against competitors who might create innovations which surpassed them (Harhoff, et al., 1999;
Lanjouw, et al., 1998; Scherer and Harhoff, 2000).
As a prerequisite of being granted, patents must be published and knowledge of the in-
vention then becomes disseminated (Johnson and Popp, 2003). Some firms do not want to pa-
tent their inventions for this reason; others do not want their patents to be subsequently cited
by others―lest knowledge of their patent’s content inspire others to invent their way around a
device that may be protected by a thicket of patents (Bessen and Meurer, 2008; Zamocin,
2013). Either way, firms invest in R&D and act as though they believe that their patents are
valuable.
R&D and patents
Competitive benefits from patenting are often examined jointly with the positive effects
of making R&D outlays (Artz, et al., 2010; Cohen, et al., 2013; Gambardella, 1992; Hall, et al.,
2005; Hedge and Sampat, 2009; Jaffe, et al., 2000; Kelley, et al., 2013; Mazzucato and Tancioni,
2012). The causal relationship between R&D outlays and benefits from patents has sometimes
Sustainability of Patent-based Competitive Advantage 8
been difficult to isolate―due, in part, to uncertainty concerning the appropriate lags to consid-
er when linking R&D outlays to the granting of patents. Because most previous studies that
have linked patent value to R&D outlays have depended primarily on patent counts and analy-
sis of patents’ patterns of forward citations (Belezon, 2011; Breitzman and Thomas, 2002; Chen,
et al., 2010; Hall, et al., 2001; Jaffe, et al., 1998; Lee, et al. 2007; Patel and Ward, 2011; Silver-
berg and Verspagen, 2007; Trajtenberg, 1990), we know that the time period between making
R&D expenditures, receiving a patent, and garnering a substantial record of citations can be ex-
tensive. Forward-citation counts have long been used as a proxy for patent value, but tests of
whether having patents makes firms more profitable than those competitors having no patents
are less abundant (and may be of interest when investigating the strength of patents as an en-
during source of competitive advantage). Similarly, tests of patent content have not yet indicat-
ed patterns that may be linked with firm profitability. Our tests of patent content use infor-
mation about backward citations (instead of the more-common forward citation estimates of
value) to assess how patents create competitive advantage.
Competitive environments that support competing technological routes (or standards)
may be especially likely to erode the viability of patent-based advantage, shorten the duration
of such advantage, or negate its strength as a competitive advantage altogether―especially
where there is greater risk of obsolescence should a firm invest in that technological route
which does not ultimately become the industry standard. Some patents may lose their viability
as a competitive advantage within turbulent settings where the chain of value created by path
dependency has been broken by the frequent discontinuities caused by technological disrup-
tion (Arikan and McGahan, 2010; Schreyögg and Kliesch-Eberl, 2007).
Sustainability of Patent-based Competitive Advantage 9
Patents in communications services
Communications services is an industry that has been subject to the type of creative destruc-
tion described by Schumpeter (1912) in which multiplexing technology multiplied the carrying
capacity of bandwidth to accommodate data and video as well as voice traffic―making simple
bandwidth investments obsolete. Some communications firms have invested heavily in re-
search and development because they presumed that the inventions which they patented
would provide them with competitive resources which could be exploited temporarily to give
them superior profitability (Gambardella, et al., 2008; Jaffe, 1986). Other firms within the same
industry have become fast followers who copied those aspects of innovations which customers
seemed to favor. Ironically, enabling technology became readily available to the fast followers
as inventors licensed the use of their patents to recover rents as quickly as possible within their
own tumultuous industries.
We investigated the effects of having patents on acquiring firms who competed in the
communications services industry during the exuberant years of internet commercialization in
order to investigate the existence and sustainability of patent-based sources of competitive ad-
vantage. Our research design was longitudinal in its scope in order to ascertain the longer-term
impact of having patents on post-acquisition operating profit margins; acquiring firms were
used as a basis for comparison because acquisitions represent an overt effort to grow the firm
via corporate renewal. For some firms, acquisitions represent their best hope of survival within
industries characterized by frequent technological evolution—especially if their in-house
knowledge absorption has been inadequate to cope with their changing competitive environ-
ment.
Sustainability of Patent-based Competitive Advantage 10
We compared the performance over time of firms having patents with that of acquiring
firms without patents and expected to find differences in firms’ profitability over time. We test-
ed for absolute differences in profitability as well as for the duration of the expected contrast in
profitability between firms who had patents versus those who did not.
Hypothesis 1a: Firms having patents will enjoy higher return-on-sales ratios than do competi-
tors within the same industry who do not have patents.
Hypothesis 1b: Firms having patents will enjoy higher return-on-sales ratios for a longer peri-
od of time than do competitors within the same industry who do not have pa-
tents.
Patents which convey sustainable competitive advantage
McGahan and Porter (1999) argued that important structural changes within an industry (e.g.,
entry, exit or effective imitation by extant competitors) drove profit levels over time to the in-
dustry’s mean―except in the case of firms possessing inimitable resources. Our second set of
hypotheses test for evidence of such an exception, i.e., firms possessing patent assets which are
more difficult for competitors to imitate are expected to extend the duration of competitive
advantage. Our method for testing these hypotheses decomposes firms’ patents into their core
and non-core knowledge antecedents.
When patents are granted, a coding system is used to describe the particular technolog-
ical areas which were combined to create the invention. The coding system also indicates the
technological areas of backward-cited patents that are listed as intellectual precedents of the
patent whose claims are being examined.1 If researchers combine their firm’s routine techno-
1 The coding system could be that of the United States Patent and Trademark Office codes (USPTO), the World Intellectual Property Organization’s International Patent Classification codes (IPC), the jointly-sponsored Co-
Sustainability of Patent-based Competitive Advantage 11
logical knowledge with external knowledge flows that are unusual and non-routine for them,
they may create new technologies (Henderson, 1993; Kim, et al, 2012; March, 1991; Sorensen
& Stuart, 2000), improve their innovative outcomes (Escribano, et al, 2009; Lane, et al, 2006;
Volberda, et al, 2010), accelerate competitive response times, and institutionalize the ability to
make radical innovations when needed (Ahuja and Katila, 2001; Cloodt, et al, 2006; Noote-
boom, et al, 2007; Tsai, 2009). Depending upon the extent of inventors’ exposure to distant
technologies and the nature of their investigative processes, firms may develop an in-house ca-
pacity for synthesizing distant technologies in their subsequent inventions (Cohen & Levinthal,
1990) or they may acquire expertise for integrating such knowledge from acquisitions. Regard-
less of how inventors gained exposure to novel technology streams and the ability to assimilate
such knowledge into their patents, we expect that having the ability to create radical techno-
logical combinations will be a source of advantage that would be more difficult for imitators to
emulate easily.
An innovation is radical in the sense that it requires inventors to process quite different
kinds of information (Henderson, 1993). Periods of radical technological change―like that
which the commercialization of the Internet represented―may have fostered the need for
greater radical innovative content to realize the Internet’s potential. In such environments, the
technological precedents that will be cited in firms’ patents may reflect the types of greater
stretches in knowledge that must be mastered to cope with such developments; these types of
inventions are similar, in spirit, to radical innovations because inventors must widen their
search range beyond their traditional comfort level to reach their scientific solutions (Dahlin
operative Patent Classification codes (CPC), or Thomson Reuters’ Derwent World Innovation Index codes (DWII), among others.
Sustainability of Patent-based Competitive Advantage 12
and Behrens, 2005; Garcia and Calatone, 2002; Green, et al., 1995; Henderson, 1993;
Schoenmakers and Duysters, 2010). Patents which stretch the limits of organizational
knowledge in this manner are risky (because such inventions may not be adopted as industry
standards), but they offer a better probability of extending the duration of competitive ad-
vantage than do innovations which merely replicate extant knowledge and capabilities in mak-
ing incrementally-novel inventions (Lin, et al, 2012; Makri, et al, 2010; Rosenkopf & Nerkar,
2001).
Audia, et al. (2000) noted that successful firms often wish to perpetuate the basis of
their past successes―even when environmental change calls for the creation of new competi-
tive resources―which is why new entrants (or smaller firms who have been acquired by incum-
bents) are expected to be the greater risk takers (who will engage in broader search activities to
formulate novel solutions to customers’ problems). Regardless of how firms became capable of
forging discontinuous technological innovations, we expect that those firms who can incorpo-
rate greater proportions of exotic, non-core knowledge into their inventions will enjoy competi-
tive advantage of longer duration―if their out-of-the-box inventions are successful at all.
Hypothesis 2a: Firms awarded patents with higher proportions of non-routine, non-core
knowledge synthesized with in them will enjoy higher return-on-sales ratios
than do competitors who do not have patents reflecting such radical inventions.
Hypothesis 2b: Firms awarded patents with higher proportions of non-routine, non-core
knowledge synthesized with in them will enjoy higher return-on-sales ratios for
a longer period of time than do competitors within the same industry who do
not have patents reflecting such radical inventions.
Sustainability of Patent-based Competitive Advantage 13
In summary, if patent assets prove not to be as unique and durable as sources of com-
petitive advantage as was hoped for, it may be because of technological obsolescence and rapid
dissemination of knowledge (or because inventors do not stretch themselves dramatically
enough in their search for ideas). In such settings, researchers would be continually searching
for new knowledge that might be integrated with their ongoing technologies to synthesize truly
unique inventions. If patent-based sources of competitive advantage are perceived to be at risk,
firms’ routines would evolve to include searches for novel uses of knowledge, greater experi-
mentation, more flexibility and frequent risk-taking activities as would be needed for firms to
become the type of moving targets whose advantages will be more difficult for competitors to
emulate (McGrath, 2001). The inventions issuing from such exploratory search activity would
be distinctive because their backward-citation patterns would differ greatly from extant patents
that may have relied extensively on building upon firms’ familiar technological areas; such
knowledge may be radically different from core areas of expertise where the firm has patented
extensively in the past. These types of inventions are radical because they have the potential to
propel industry evolution and promote synergistic technological progress (Gambardella and
Torrisi, 1998; Malerba, 2006; Mowery and Rosenberg, 1998; Nelson and Winter, 1982). Expo-
sure to outsiders’ ideas will also exacerbate the pace of technological change―as has occurred
in many industries where specialist firms have shared knowledge through their strategic alli-
ances (Harrigan, 1985) or in other arrangements that accelerated the diffusion of knowledge.
Methodology
Our tests of the sustainability of patent-based competitive advantage used post-acquisition
analyses of the operating margins of firms who acquired targets in the communications services
Sustainability of Patent-based Competitive Advantage 14
industry between 1998 and 2005. For parallelism, the performance of acquiring firms with and
without patents are compared. We track the post-acquisition profitability of their recovery
years (after integrating their acquisitions) and beyond―using the acquisition year as a common
benchmark for comparison.
Although it appeared to be a highly-attractive industry―due to its rapidly-growing de-
mand and the spectacular stock market valuations of firms operating therein―the communica-
tions services industry lost its luster when firms’ capacity expansions outran the demand of cus-
tomer firms to absorb it; the average operating margins of telecommunications carriers were
low – especially for the newer-technology lines of business. Rapid rates of technological obso-
lescence shortened the recovery time available for some communications firms to justify their
capital expenditures as multiple technological modes competed to carry voice, data and video
content during this era. A competitive shake-out was inevitable.
Acquisitions included in sample
Our window of analysis―U.S. firms’ operating margins from 1998 through 2012 (depending
upon when a particular acquisition was consummated and integrated with ongoing opera-
tions)―included a period of rapid industry growth from 1998 through 2005 when overall com-
munications revenues grew by 60% (by an average of 8.5% per year). Within this growth trend,
some communications products faced declining demand while other products thrived. For ex-
ample, revenues (and profits) from wireless telecommunications services surpassed revenues
from wireline services during 2008 and thereafter (Bureau of Census, 2014); industrywide reve-
nues for wireline communications services actually began declining as early as 2000 (Bureau of
Census, 2014). Some firms entered the communications industry by pricing services below their
Sustainability of Patent-based Competitive Advantage 15
fully-allocated costs in an effort to buy market share; other firms reported negative operating
margins because they spent heavily on research and development to produce patentable inven-
tions (or incurred acquisition premiums which they could not amortize in a timely fashion).
Thomson One’s Mergers & Acquisitions database (2013) reported that (between 1998
and 2005) 2,028 acquisitions were made of target firms which provided wired telecommunica-
tions (landlines) in NAICS 517110, wireless telecommunications (composed of cellular and/ or
paging services) in NAICS 517210, satellite telecommunications in NAICS 517410 (and resellers
of trunk line capacity in NAICS 517911), cable and other program distribution services in NAICS
515210, and/ or other communications services in NAICS 517919.2 Some firms also provided
broadcast (NAICS 515120), media (NAICS 512110) or internet services (NAICS 519130) because
they were thusly-diversified when the acquisition of interest occurred. COMPUSTAT financial
data (2013) were available for 1,194 of those reported transactions. Because some acquiring
firms closed more than one communications services transaction in one or more of the years
that were included in our eight-year observation window, transaction details for each acquiring
firm were combined for each respective year to yield 606 usable observations representing 309
distinct firms and covering eight years of acquisition activities. Some firms made acquisitions in
multiple years and 360 of those observations involved firms who had patents. Our post-
acquisition patent scores included the combined patent outputs of acquiring and target firm;
pre-acquisition patent scores included the patents of acquiring firms only.
2 NAICS code 517919 included dial-up, online access to Internet, or VoIP service providers (using client-supplied telecommunications connections; earth stations (except satellite telecommunication carriers); satel-lite tracking stations; radar station operations; satellite telemetry operations and/ or telemetry and tracking system operations on a contract or fee basis.
Sustainability of Patent-based Competitive Advantage 16
--------------------------------------------- Exhibits 1a, 1b, 1c and 1d here
--------------------------------------------- Financial variables
Exhibit 1 describes the variables used in testing our hypotheses; we present means and correla-
tions for the sample with and without patents. Our dependent variable, Return on sales (ROS),
was calculated by dividing earnings before interest, taxes, depreciation and amortization
(EBITDA) by revenues; ROS is also called the firm’s operating margin percentage because it indi-
cates profitability from operations (before financing charges and allowances for future capital
expenditures were deducted). In undiversified firms, return on sales ratios would indicate their
profitability within a specific industry. Our use of the operating margin percentage as a per-
formance measure captured the relative profitability of those firms that acquired one (or more)
communications services firms during the years of 1998 through 2005. We tracked their post-
acquisition operating margin percentages for as many as ten years after their transaction was
consummated and interpreted their ROS ratios as indications of the relative post-acquisition
profitability of their respective strategic postures. As acquiring firms were themselves acquired
(or went bankrupt), the number of observations per year thereafter declined until the depend-
ent variable eventually reflected only the strong performance of surviving firms.
During the years of 1998 through 2005, the communications services industry was char-
acterized by aggressive competitive behaviors (that adversely affected operating margin per-
centages) and the use of optimistic accounting practices whereby operating losses sometimes
exceeded firms’ sales volumes. These losses occurred as communications firms expended funds
in anticipation of demand for their product offerings during a bubble period when firms felt
great urgency to capture market share. Such optimistic “Internet accounting” policies extend-
Sustainability of Patent-based Competitive Advantage 17
ed, in particular, to high levels of research and development (R&D) expenditures as numerous
firms invested heavily in competing innovations without evidence of their commercial poten-
tial. On average, R&D expenditures per sales were higher in the four years immediately after an
acquisition was made than they were in subsequent years―indicating a spurt in research and
development outlays which may have included some of the costs of integrating acquired re-
search facilities. Return on sales ratios were typically lower in the first years after an acquisition
occurred―which may reflect the additional R&D outlays expended to create inventions from
unusual knowledge antecedents. Because research expenditures may impair short-term profit-
ability (but ultimately yield patents which convey competitive advantage), R&D variables were
lagged in our model specifications for testing the effects of having patents.
--------------------- Figure 1 here
---------------------- The year of each consummated transaction was coded as ROS0 to track its respective,
post-acquisition improvement in profitability over time. In the pooled sample of Figure 1, the
average return on assets performance of firms without patents is very similar to that of those
firms who had patents before making their acquisitions and continued to patent after their
transaction had closed. We note that only the subset of firms who acquired their patents via
acquisition (and had no patents prior to their transaction) enjoyed superior average return on
sales ratios over the post-acquisition time that we tracked.
--------------------- Figure 2 here
---------------------- Figure 2 reveals that―except for transactions consummated in 2003―average post-
acquisition return on sales ratios were highest for firms who acquired their patents via acquisi-
Sustainability of Patent-based Competitive Advantage 18
tion (and had no patents prior to their transaction). The year-by-year analysis indicates that av-
erage post-acquisition operating-margin percentages of firms without patents were similar to
those of firms with a history of patenting before and after consummating their transactions.
The visual evidence suggests that Hypotheses 1a and 1b cannot be accepted.
We tested post-acquisition return on sales ratios as dependent variables for several
years after an acquisition had been consummated and found that the average, incremental
post-acquisition improvements in return on sales changed their slope by the fourth year after
an acquisition was consummated. Indeed, Figure 1 shows that average operating-margin per-
centages converged by year5, regardless of whether the firm had patents or not. Average oper-
ating margin percentages increased more slowly after year4―suggesting that (on average) im-
provements enjoyed from integrating a particular acquisition were fully-realized by year4 and
something more was needed to push return on sales ratios higher.
Figure 2 examines average post-acquisition return on sales ratios by the year when the
transaction closed; it shows that average post-acquisition return on sales ratios tended to con-
verge over time for transactions that closed during the most-turbulent years of competition.
We had expected that the operating margin percentages of surviving firms would be higher if
they had patents, but Figure 2 suggests that only firms with newly-acquired patents were a sig-
nificant discriminator of ROS performance – especially after the industry’s competitive shake-
out in which 48 percent of acquiring firms were themselves acquired (or liquidated). Of particu-
lar interest is the poor performance of those “old-economy” firms who had patents before ac-
quiring in 1998 and 1999, but were not awarded patents subsequently. Their low average long-
Sustainability of Patent-based Competitive Advantage 19
term performance suggests that they were also on the road to bankruptcy (or acquisition) in
the years after 2008 (which is when our financial data for them ended).
Backward-citation patent scores
Our patent-scoring methodology created annual, aggregated scores for firms’ patents that were
constructed of “core” scores that characterized the technological areas in which the claims of
each respective patent were granted and “non-core” scores that characterized the antecedent,
“non-core” technology class codes that were different from those technology class codes that
were assigned to a particular patent. Each patent score was weighted by the frequency with
which particular dyads of technology class codes appeared together in patents granted in a par-
ticular year (relative to the frequency of all of the other possible dyads of technology class
codes for all patents granted in that respective year). A high score represented a synthesis of
technological precedents from a broad range of technological classification codes, while a low
score reflected that a patent’s backward citations came from a narrower array of technological
classification codes.
V-score as corrected total patent score
Because our patent-score methodology allowed for the inclusion of a large number of different
core (and non-core) technology class codes for each patent, the calculations were done in a
spreadsheet matrix that juxtaposed each core technology class code with itself and all other
technology class codes. Rows represented core- as well as non-core codes; columns represent-
ed the core technology class codes awarded to a particular patent. The weightings by which
counts of the frequency of each technology class code were adjusted used averaged probabili-
ties for each dyad of technology class codes occurring (modified annually for each patent
Sustainability of Patent-based Competitive Advantage 20
year).3 The backward-citation patent score, V, was equal to the Raw Innovation Score (the sum
of the core score and non-core score)―multiplied by a correction factor, [fo/fi], which was
the ratio of the count of outside-the-core technology class codes divided by the ratio of the
count of inside-the-core technology class codes:
V = ([ai,ao ffk]k) [fo/fi]
The correction factor decomposed the sum of all technology class codes according to whether
they were inside-the-core or outside-the-core. The factor score was a useful criterion for sort-
ing patents by their mix of content.
Raw score as core and non-core scores
The Raw Innovation Score, Wk, was the sum of all weighted scores for all technology class codes
appearing in a particular patent, ([ai,ao ffk]k), and it was also the sum of the core score and
non-core score―which means that each component of Wk could be investigated separately.
Using the convention that in represented n- different inside-the-core technology class codes
that may appear in a patent and om represented m- different outside-the-core technology class
codes that may have been cited by that patent, we calculated the average dyad weighting, ai or
ao, for each respective technology class code as:
ai = pj/in for inside the core (and ao = pj/om for outside the core)
where pj was the dyad weighting for a particular core (or non-core) technology class code ap-
pearing with itself or with another backward-cited technology class code and j equaled n times
(n + m). Each technology class code’s frequency factor, ffk, was calculated as:
3 The probabilities per dyad occurring were based on the actual probability for the patent’s earliest priority date―which was the year of the first USPTO filing related to the patent that was ultimately granted.
Sustainability of Patent-based Competitive Advantage 21
ffk = fk/F
where fk was the frequency with which a technology class code occurred in a particular patent
and F was the sum of all technology class codes appearing in that patent and k equals 1, 2, …, n,
n+1, …, n + m. The frequency factor was multiplied times the average dyad rating per technolo-
gy class code and summed according to whether the technology class code was inside-the-core
or outside-the-core in the patent award. The core and non-core scores were added together to
create the Raw Innovation Score―which was multiplied by the ratio of non-core to core tech-
nology class code counts.
Weighting the frequency of technology class codes.
The weightings by which the frequency of core and non-core technology class codes were
summed in our patent-score index used the actual annual frequency with which specific dyads
of technology class codes appeared (relative to all of the other possible dyads that could have
appeared together in a particular year). The matrix of interaction dyads formed a Reference Ta-
ble; the weightings in each year’s Reference Table were adjusted annually to reflect the near-
ness of technological confluence that was evolving as knowledge was diffused.
Our weighting of the frequency of technology class codes differed from Hall, et al.
(2001)’s operationalization of Trajtenberg, et al.’s (1997) backward-citation patent score in
three important ways. First, Hall, et al. (2001) assigned weightings based on the frequency with
which codes occurred. Second, they did not distinguish the effects of core from non-core tech-
nology class codes in calculating each patent’s score. Third, Hall, et al. (2001) did not adjust
their weightings of their index to reflect the rate of technological change occurring―which ac-
celerated over time within many industries, including communications services.
Sustainability of Patent-based Competitive Advantage 22
We used the technology coding system associated with the Derwent World Patents In-
dex (2013) to calculate our patent scores. The logic of our patent-scoring methodology is con-
sistent with the framework suggested by Trajtenberg, Henderson and Jaffe (1997)―which was
operationalized in Hall, Jaffe and Trajtenberg (2001)―but it utilized 289 technology class codes
for classification instead of their 36 classification codes (and counts of the occurrence of various
codes were weighted by frequency measures according to each respective year’s distribution of
all patents awarded to all firms―instead of using the Trajtenberg, et al (1997) system of
weighting when building our scores). The weighting by which the Raw Innovation Score was
multiplied gave emphasis to those patents which built upon novel technological class
codes―since those patents could represent a fruitful pattern of synthesizing knowledge from
diverse fields. A firm’s patent scores were aggregated on a year-by-year basis. Both 4-year and
7-year averages were also constructed by summing averaging the yearly patent scores accord-
ingly.
In using patent scores to represent firms’ sources of technological advantage, we ac-
cepted the cautions of Jaffe, et al., (2000) that lawyers and professional patent examiners add-
ed over two-thirds of the cited antecedents that were contained in firms’ patent applications
(Alcacer and Gittleman, 2006; Gittleman, 2008). We assumed that the various areas of techno-
logical knowledge which the backward citations indicated had been synthesized within a partic-
ular invention were appropriately cited―whether inventors themselves could identify the spe-
cific patented antecedents (or not). We inferred that inventors engaged in exploratory learning
to understand the novel technologies which they synthesized when patent scores were high;
we inferred that inventors relied on extant knowledge when their patent scores were low. We
Sustainability of Patent-based Competitive Advantage 23
expected that high patent scores would support higher return on sales ratios and that the dura-
tion of this particular source of competitive advantage would be greater than for less-complex
sources of advantage.
-------------------------------- Figures 3 and 4 here
-------------------------------- Figure 3 shows that for most years in the pooled sample, the highest average return on
sales ratios were enjoyed by acquiring firms with higher backward-citation patent scores. In
Figure 4, which examines operating margin percentages on a year-by-year basis (depending on
when a transaction closed), firms with high backward-citation patent scores enjoyed the high-
est average performance in half of the years examined. Firms having no patents had the high-
est average return on sales ratios in the four years when the competitive shakeout occurred in
communications services (which were the years 2000 through 2003).
Control variables
The logarithm of total assets is specified as a control variable in many models to test the effect
of firm size on return on sales because scale economies (and large market share) have long
been viewed as being important sources of competitive advantage; we were curious to know
whether size was harmful to strategic flexibility in such a turbulent competitive environment as
communications services and included it in our model specifications.
The effect of diversification was approximated by constructing a concentric NAICS-based
index that combined the distances of the acquiring firm’s lines of business (and those of the
target firm) from the NAICS code representing the combined firm’s primary line of business.
The effect of capital intensity was approximated using the ratio of total assets to number of
employees, and employee productivity was approximated by using the ratio of total revenues
Sustainability of Patent-based Competitive Advantage 24
to number of employees. R&D intensity was specified as the ratio of R&D expenses to sales and
R&D productivity was approximated as the number of annual patents awarded divided by R&D
expenses. Dummy variables were added to represent the combined firm’s presence in wired,
wireless, and internet services, among others. The line-of-business variables were not mutually
exclusive; many firms in our sample engaged in multiple lines of business simultaneously.
Results
Tests of patent-based effects over time on firms’ operating margin percentages suggested that
a strong and persistent relationship existed between return on sales ratios and those patent
scores which indicated higher novelty in the knowledge antecedents which patents built upon,
but the simple effect of having patents waned in significance in the years after an acquisition
was consummated. Not only did patent score variables have positively-signed and statistically-
significant coefficients in tests of post-acquisition returns on sales, but change variable analysis
showed particularly strong results in the return on sales performance of early years. Neverthe-
less results ultimately suggested that patent-based sources of competitive advantage were of
limited duration in their significance in both of our models of patent-based sources of competi-
tive advantage.
--------------------- Exhibit 2 here
---------------------- Effect of having patents
Six models tested the effects of having patents on the return on sales ratio for the first five (and
then seventh) post-acquisition years (which are coded as ROS1, ROS2, … ROS7, respectively). In
Exhibit 2, the sign of the having patents variable was positive and statistically-significant for the
first four years after an acquisition was consummated; the variable becomes negative thereaf-
Sustainability of Patent-based Competitive Advantage 25
ter―suggesting that patents are no longer an effective discriminator of return on sales perfor-
mance. Results suggested that the post-acquisition, incremental advantage on operating mar-
gins of simply having patents was not sustainable for long; more sources of advantage were
needed over time―a finding which was consistent with D’Aveni’s (1994) notion of hypercom-
petition and McGrath’s (2013) argument that competitive advantage is not sustainable.
In all six models tested in Exhibit 2, the signs of the research and development to sales
variables were negative and statistically-significant (which was not surprising since R&D ex-
penses were deducted from gross margin when computing the operating margin percentages).
Each R&D variable was lagged relative to the dependent variable being tested by an average of
two years in order to approximate the effects of research outlays on future operating margin
percentages; their signs were highly significant in all six models tested. The signs of debt as a
proportion of total assets (leverage) ratios were positive (which was also not surprising since
interest expenses were deducted after calculating EBITDA); results suggested that carrying debt
was temporarily helpful to building a strategic posture that would sustain premium prices. The
capital intensity variable was negative when it was not significant; the sign of the assets-to-
employee ratio was significant and highly-significant in year4. The logarithm of assets variable
was positive and highly-significant in post-acquisition year5 and year7―suggesting that the cost
leadership strategy (which depended on scale economies and higher market share as a source
of advantage) grew more important as time passed and other sources of advantage proved to
be fleeting.
The sign of the wireline services variable was negative and weakly significant (if at all).
The sign of the wireless services variable was not significant in any specifications shown; nor
Sustainability of Patent-based Competitive Advantage 26
was the internet services variable. In the many specifications tested, a pattern emerged
whereby the sign of the wired (landline) services variable was initially negative but became pos-
itive and significant by the seventh post-acquisition year (reflecting the evolution of wireline
services into cash-cow status as the business faced declining demand and marginal firms yield-
ed their laggard customer lists to competitors with greater staying power). The coefficients of
the wireless services and internet access dummy variable followed the opposite pattern where-
by they started positive and became negative over time, suggesting that competitors in those
communications services suffered declining operating margin percentages over time.
Results from Exhibit 2 suggested a competitive scenario in which patents made positive
contributions to operating margin percentages during the early years when acquisitions were
being integrated, but their incremental impact waned unless firms’ technological diversification
was successful in continuing to expand the breadth of knowledge that their inventors synthe-
sized in patents over time. Hypothesis 1a is supported by results, but Hypothesis 1b cannot be
accepted.
--------------------- Exhibit 3 here
---------------------- Effect of patent scores
Exhibit 3 illustrates results on operating margin percentages of specifications in which patent
score variables were substituted for the simple “having patents” variable tested in Exhibit 2.
Results shown in Exhibit 3 reflect the operating margin percentages of those firms for which
post-acquisition patent scores could be calculated (as contrasted with Exhibit 2 where all ac-
quiring firms were included for which financial information was available). There is some sup-
port for Hypotheses 2a and 2b because, in Exhibit 3 (which considers the effect of patent scores
Sustainability of Patent-based Competitive Advantage 27
on their return on sales ratios), the signs of all patent score variables were positive and statisti-
cally-significant―which suggests that creating patents which integrate larger proportions of
non-core knowledge will continue to influence firms’ operating margin percentages positively
for a greater duration.
Firms’ average patent score values trended towards mean values over time―perhaps
because individual firms no longer synthesized knowledge in their patents that was far from
their comfort zones (as was reflected by the technology class codes in which their subsequent
patents were granted). Or perhaps their patent scores trended towards mean values over time
because industrywide technology convergence had evolved in such a manner that when partic-
ular combinations of technology dyads appeared together as knowledge antecedents in any
particular patent’s grant, those technology class codes were no longer extraordinary in their
nature vis-à-vis what competitor firms were synthesizing in their respective inventions. The pa-
tent scoring methodology weighted the impact of out-of-the-box technology antecedents more
heavily than backward citations of technology class codes that were the same as those technol-
ogy class codes in which the patent’s claims were granted; in Exhibit 3, having many out-of-the-
box patents continued to improve firms’ return on sales ratios―even in year7.
In Exhibit 3, the signs of all ratios of research and development-to-sales variables were
negative and statistically-significant (which was not surprising since R&D expenses were de-
ducted from gross margin when computing return on sales). The post-acquisition significance of
the R&D-to-sales coefficients decreased over time. When the research productivity variable
―measured as the ratio of patents-to-R&D expenses―was tested, it was positive and weakly
Sustainability of Patent-based Competitive Advantage 28
significant (which suggested that high R&D productivity improved firms’ returns on sales and
sustained the duration of their patent-based competitive advantage).
Signs were positive and statistically-significant for the coefficient of the assets-per-
employees variable (representing capital intensity) as well as for the logarithm-of-assets varia-
ble (suggesting the presence of scale economies). The diversification variable was weakly signif-
icant and not included in specifications as the number of usable observations decreased. (The
population of usable post-acquisition observations decreased over time because 48.5 percent
of the acquiring firms were themselves acquired by 2012 and another 9.9 percent of the acquir-
ing firms became insolvent. On average, the subsequent transactions by which acquiring firms
were themselves acquired occurred five years after the acquisition that closed in year0. )
Tests of the line of business dummy variables in Exhibit 3 again indicated that wired
communications services (landlines) were negatively-signed and significant in the early post-
acquisition years, but became positive and significant by year7. Although it was not statistically-
significant in Exhibit 3, the sign of the wireless services variable was negative over time. The
internet services variable was negative and significant by year7 (but not by year4). Consistent
with findings from Exhibit 2, results indicated that firms’ operating margin percentages were
eroded by competing in hotly-contested lines of business during those years when their respec-
tive, apparent attractiveness attracted entry; by contrast the relatively fewer competitors that
provided services which faced declining demand enjoyed a positive impact on their operating
margins. Results suggested that endgame businesses offered opportunities for higher operat-
ing margin percentages than did those businesses for which demand was still growing and the
nature of competitive rules for some lines of business were still emerging. Results suggest that
Sustainability of Patent-based Competitive Advantage 29
firms’ higher return on sales ratios may have been due, in part, to their continued participation
in lines of business for which demand was declining (Harrigan, 1980).
--------------------- Exhibit 4 here
---------------------- Effect of changes in patent scores and R&D expenditures
Results of our tests of the effects of change variables were limited by the small sample sizes
that resulted when comparing year-by-year patent scores; many firms in our sample were not
awarded patents in any of the years that we tracked. Where data were available, we found that
positive changes in post-acquisition patent scores were significantly associated with positive
changes in firms’ return on sales ratios for the first four years after a transaction; the sign of the
patent-score change variable became negative and significant in year5―which reflected the be-
ginning of the flattened pattern of incremental changes in operating margin percentages that
we observed in our sample which is shown in Figures 1 and 2. Some firms continued to include
radical technology class codes among the antecedents that were cited in their patents, but their
innovation was no longer rewarded by incremental improvements in return on sales ratios after
year6 for reasons that we have already speculated about (concerning changes in relative novel-
ty as industry structure evolved) .
None of the post-acquisition changes in R&D productivity variables that we specified
were significant predictors of changes in operating margin percentages in any of the years test-
ed. The logarithm of assets variable (denoting scale-economy advantages) was weakly-
significant only in the third model specified. Results suggest that patent-based sources of com-
petitive advantage were of limited duration in the communications services industry during the
years spanning 1998 through 2012. Year-by-year analysis suggests that surviving communica-
Sustainability of Patent-based Competitive Advantage 30
tions firms enjoyed limited competitive advantage from having patents―unless the content of
their patent scores indicated that firms were stretching the breadth of technological class codes
that were synthesized in their patent applications.
Discussion of Results and Implications
Results are unsettling since patents have long been viewed as providing a quasi-monopolistic
advantage over specific inventions for a specified period; firms spend on research and devel-
opment aggressively with the expectation that such outlays will be recovered through the abil-
ity to charge temporary monopoly rents for exploitation of their patented inventions. Results
suggest that competitive stakes increased dramatically for firms who were patenting within the
communications services industry where monopoly rents from patents could be collected for
no more than five years. Results support the findings of Bessen and Meurer (2008) and others
who argue for the abolishment of the patent system, in part because the system has unintend-
ed economic consequences.
Our tests using return on sales ratios were run on a sample of acquiring firms having
some degree of diversification into more than one line of business.4 Although the firms in our
sample were diversified to varying degrees, we sorted the observations by line of business (and
by year) to understand how operating margin percentages changed over time and noted that
firms having media properties within their corporate families enjoyed positive average return
on sales margins; sorting the sample on all other lines of business yielded negative average op-
erating margin percentages for the period of 1998 through 2000. By 2001, firms having broad-
4 Approximately 55 percent of the acquiring firms were single-business entities; 79 percent of them were en-gaged in at two NAICS-defined lines of business and 90 percent of them were engaged in at least three lines of business when the acquisitions occurred. Roughly 45 percent of the target firms were single-business enti-ties; 68 percent of targets were engaged in only two (or fewer) NAICS-defined lines of business and only 79 percent of them were engaged in three (or fewer) lines of business when the acquisitions occurred.
Sustainability of Patent-based Competitive Advantage 31
cast assets in their corporate families enjoyed positive average return on sales margins (but av-
erage operating margin percentages were sometimes negative in subsequent years for this
sorting). Average operating margin percentages became positive for wired (landlines) commu-
nications services in 2003―as well as for resellers of capacity from inter-exchange communica-
tions carriers. Average return on sales margins became positive in 2004 for firms having satel-
lite service providers in their corporate families. By 2006 firms offering wireless communica-
tions services enjoyed positive average return on sales margins (but their average operating
margin percentages were negative during 2008 through 2010 for this sorting). The average op-
eration margin percentages of firms engaged in cable network communications services
(among other lines of business) became positive in 2007. On average, the return on sales mar-
gins of firms that offered internet-related communications services (among other lines of busi-
ness) did not become positive until 2010. (When the sample was sorted on NAICS 517919, indi-
cating Internet services, firms’ average operating margin percentages remained negative until
2011.)
Limitations
Conclusions from our tests were limited because a more-thorough test of the sustainability of
patent-based advantages within the communications services industry should have compared
the profitability of non-acquiring firms with that of the firms in our sample. Unfortunately there
were few non-acquiring firms in the communications services industry who also held patents.
Acquisitions appeared to be the method by which firms grew within the highly-dynamic com-
munications services industry (while they also persisted in developing patentable innovations),
so our sample may have approximated the available universe of firms during 1998 through
Sustainability of Patent-based Competitive Advantage 32
2005. Tests were hindered for examining the effects of patents on return on sales by the high
proportion of acquiring firms who were themselves acquired after consummating the initial ac-
quisitions that put them into our window of observation.
Because there was less attrition among electronics firms who made acquisitions during
our window of 1998 through 2005, we also tested the duration of patent-based competitive
advantage using an electronics sample to compare their respective patterns with that of the
communications services firms; operating margin percentages were lower for the electronics
industry—suggesting an even more turbulent competitive setting. In the electronics sample,
the coefficient of the “having patents” variable was positive and significant for post-acquisition
years 1 and 2; then the signs of each post-acquisition year’s patent variable became negative
(but not significant until year6). The post-acquisition sign of having patents again became posi-
tive and significant in year6 in electronics and remained so until post-acquisition year10 (alt-
hough the coefficients were not always significant). Results suggest that patent-based ad-
vantages therein may also have been eroded during years of particularly intense competition in
the electronics industry―just as they were within the communications services industry.
So many studies have indicated that patents were valuable by using analysis of forward
patent citations that we also tested forward patent scores using the same construction meth-
odology (yielding scores with higher values for patents having citations from broadly-disparate
user groups). Tests of ROS4 and ROS7 (using 4-year averaged forward-patent scores that were
lagged by three years for tests of ROS7) and for ROS7 and ROS8 (using 7-year averaged forward-
patent scores) returned negative, significant results. Further investigation of the effects of year-
by-year forward-citation patent scores on firms’ operation profit margin percentages may be
Sustainability of Patent-based Competitive Advantage 33
warranted―as well as theoretical explanations for why these patent-score measures should be
negatively correlated with return on sales. Our preliminary conclusion of such results is that av-
erage operating margins are damaged by having the firms’ patents built upon by firms in di-
verse technological areas that created substitute products which competed with the firms’ in-
ventions (but results may be due to our lack of information about actual patent royalties that
were collected from users―if any).
Summary
Our results suggest that competitive advantages from patents are limited in duration. Results
concerning the predictive power of post-acquisition patent scores offer some respite for firms
that continue to patent their inventions―provided that firms’ research organizations continue
to integrate technological knowledge that is far from their traditional technological areas within
their respective inventions. Exploratory learning continues to be a mandatory organizational
activity for firms that intend to survive―especially within industries characterized by rapid
technological change.
Success at serving customers attracts entry―whether by new firms who were previously
lurking on an industry’s fringe or by nearby competitors (who make investments to reposition
themselves in order to serve the newly-attractive customers which they wish to capture).
Firms’ incremental investments go to those competitive arenas where there appear to be
promising returns and (unless demand is growing rapidly) those investments in assets and ca-
pabilities are followed by the inevitable excess capacity and price cutting behavior that is need-
ed for new entrants to reach breakeven volumes of sales. Even in rapidly-growing environments
where incumbent firms acquire to gain technology, competitive advantage from patent assets is
Sustainability of Patent-based Competitive Advantage 34
transient and the need to renew the firm’s resources and organizational capabilities never
ends.
Sustainability of Patent-based Competitive Advantage 35
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Sustainability of Patent-based Competitive Advantage 43
Figure 1
-20%
-10%
0%
10%
20%
30%
40%
Post-Acquisition Return on Sales for All Transactions
Always Patents Before Only After Only Never Patents
Sustainability of Patent-based Competitive Advantage 44
Figure 2 Comparison of Return on Sales by Year of Acquisition
-100%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-Acquisition Return on Sales for 1998 Transactions
Both Before/ After Before Only After Only No Patents
-100%
-80%
-60%
-40%
-20%
0%
20%
40%
60%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-acquisition Return on Sales for 1999 Transactions
Both Before/ After Before Only After Only No Patents
Sustainability of Patent-based Competitive Advantage 45
Figure 2 (continued)
-60%
-40%
-20%
0%
20%
40%
60%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-Acquisition Return on Sales for 2000 Transactions
Both Before/ After Before Only After Only No Patents
-60%
-40%
-20%
0%
20%
40%
60%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-Acquisition Return on Sales for 2001 Transactions
Both Before/ After Before Only After Only No Patents
Sustainability of Patent-based Competitive Advantage 46
Figure 2 (continued)
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
50%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-Acquisition Return on Sales for 2002 Transactions
Both Before/ After Before Only After Only No Patents
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
50%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9
Post-Acquisition Return on Sales for 2003 Transactions
Both Before/ After Before Only After Only No Patents
Sustainability of Patent-based Competitive Advantage 47
Figure 2 (continued)
0%
10%
20%
30%
40%
50%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8
Post-Acquisition Return on Sales for 2004 Transactions
Both Before/ After Before Only After Only No Patents
0%
5%
10%
15%
20%
25%
30%
35%
40%
45%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7
Post-Acquisition Return on Sales for 2005 Transactions
Both Before/ After Before Only After Only No Patents
Sustainability of Patent-based Competitive Advantage 48
Figure 3 Comparison of Post-Acquisition Return on Sales by Backward-Citation Patent Scores
-10%
-5%
0%
5%
10%
15%
20%
25%
30%
35%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Average Post-Acquisition Return on Sales
High Scores Low Scores No Patents
Sustainability of Patent-based Competitive Advantage 49
Figure 4 Year-by-Year Comparison of Return on Sales by Backward-Citation Patent Scores
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-Acquisition Return on Sales for 1998 Transactions
High Scores Low Scores No Patents
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-Acquisition Return on Sales for 1999 Transactions
High Scores Low Scores No Patents
Sustainability of Patent-based Competitive Advantage 50
Figure 4 (continued)
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-Acquisition Return on Sales for 2000 Transactions
High Scores Low Scores No Patents
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-Acquisition Return on Sales for 2001 Transactions
High Scores Low Scores No Patents
Sustainability of Patent-based Competitive Advantage 51
Figure 4 (continued)
-20%
-10%
0%
10%
20%
30%
40%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9 ROS10
Post-Acquisition Return on Sales for 2002 Transactions
High Scores Low Scores No Patents
-60%
-50%
-40%
-30%
-20%
-10%
0%
10%
20%
30%
40%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8 ROS9
Post-Acquisition Return on Sales for 2003 Transactions
High Scores Low Scores No Patents
Sustainability of Patent-based Competitive Advantage 52
Figure 4 (continued)
-20%
-10%
0%
10%
20%
30%
40%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7 ROS8
Post-Acquisition Return on Sales for 2004 Transactions
High Scores Low Scores No Patents
0%
5%
10%
15%
20%
25%
30%
35%
40%
ROS0 ROS1 ROS2 ROS3 ROS4 ROS5 ROS6 ROS7
Post-Acquisition Return on Sales for 2005 Transactions
High Scores Low Scores No Patents
Sustainability of Patent-based Competitive Advantage 53
Exhibit 1a
Means for Having Patents
N Mean Std Dev Minimum Maximum
1 LogAssets0 441 3.26115 1.17469 -0.91364 5.9414
2 LogAssets1 543 3.22743 1.17613 -0.70774 5.98373
3 LogAssets4 414 3.22146 1.1977 -0.91364 5.87535
4 LogAssets7 317 3.4574 1.15493 -0.30103 5.90055
5 Productivity0 393 0.31867 0.39453 0.001 4.89267
6 Productivity1 469 0.38561 1.06022 0.00119 19.991
7 Productivity7 299 1.06584 4.90317 0.00741 71.9765
8 Assets/ Employees0 351 14.5074 102.334 0.02146 1732
9 Assets/ Employees1 460 19.3452 136.348 0 2289
10 Assets/ Employees7 300 3.16357 11.2369 0.05033 108.7581
11 Intangibles/ All Assets0 287 0.22295 0.21047 0 0.89174
12 Intangibles/ All Assets1 391 0.2086 0.21297 2.84E-06 0.95649
13 Intangibles/ All Assets7 293 0.31621 0.21667 0.000262 0.83651
14 Long-Term Debt/ Assets4 359 0.35301 0.24614 0.00016 0.95498
15 Has Patents 606 0.59406 0.49148 0 1
16 Landline (Wired) Services 606 0.72277 0.448 0 1
17 Wireless Services 606 0.49505 0.50039 0 1
18 Internet Services 606 0.19142 0.39374 0 1
Sustainability of Patent-based Competitive Advantage 54
Exhibit 1b
Correlations for Having Patents
1 LogAssets0 1 2 3 4 5 6 7 8 9 10
2 LogAssets1 0.86732
<.0001
414
3 LogAssets4 0.73134 0.80404
<.0001 <.0001
300 386
4 LogAssets7 0.73579 0.80052 0.93833
<.0001 <.0001 <.0001
225 288 307
5 Productivity0 0.09357 0.01006 0.21193 0.13623
0.0804 0.8478 0.0004 0.0492
350 366 275 209
6 Productivity1 -0.1282 -0.0885 0.03703 0.24831 0.32478
0.0155 0.0612 0.4956 <.0001 <.0001
356 448 341 255 348
7 Productivity7 -0.0091 -0.0345 -0.0329 -0.0867 0.05344 0.01799
0.8953 0.5723 0.5768 0.1349 0.4535 0.778
213 271 291 299 199 248
8 Assets/ Employees0 0.17912 0.15129 -0.089 -0.1344 0.08889 0.02217 -0.0217
0.0007 0.0057 0.1648 0.0674 0.0969 0.6974 0.774
351 332 245 186 350 310 177
9 Assets/ Employees1 0.13273 0.11316 -0.0467 -0.0999 0.22399 0.01363 -0.0128 0.49829
0.0124 0.0157 0.3943 0.1158 <.0001 0.7723 0.8428 <.0001
354 455 335 249 340 453 241 307
Sustainability of Patent-based Competitive Advantage 55
10 Assets/ Employees7 -0.0419 -0.0206 -0.0107 0.01631 0.04044 0.19959 0.54159 -0.0261 -0.0006
0.5425 0.7353 0.8561 0.7784 0.5706 0.0016 <.0001 0.7303 0.9929
214 272 291 300 199 248 299 177 241
11 Intangibles/ Assets0 -0.1132 0.01737 0.06637 0.01634 -0.0064 -0.0475 -0.053 -0.1224 -0.1153 -0.0476
0.0553 0.7767 0.3432 0.8335 0.9178 0.464 0.507 0.0469 0.0759 0.551
287 269 206 168 263 240 159 264 238 159
12 Intangibles/ Assets1 -0.0174 -0.0965 0.13514 0.08644 0.07732 0.06106 -0.093 -0.1167 -0.139 -0.0975
0.7642 0.0566 0.0194 0.1934 0.207 0.256 0.1704 0.067 0.0092 0.1505
300 391 299 228 268 348 219 247 350 219
13 Intangibles/ Assets7 0.16798 0.1457 0.18817 0.21034 -0.009 -0.0602 -0.0265 -0.1484 -0.0987 -0.0672
0.0153 0.0176 0.0014 0.0003 0.9014 0.3549 0.6566 0.0513 0.1339 0.26
208 265 285 293 192 238 283 173 232 283
14 LT Debt/ Assets4 0.07418 0.10797 -0.0088 -0.0106 -0.0063 -0.0482 0.12918 0.03027 0.05021 0.24113
0.2288 0.049 0.8682 0.8621 0.9225 0.4076 0.0381 0.6567 0.3942 <.0001
265 333 359 273 241 297 258 218 290 258
15 Has Patents 0.34531 0.33698 0.39524 0.34789 0.01431 -0.0685 -0.1244 -0.0337 -0.0845 -0.0961
<.0001 <.0001 <.0001 <.0001 0.7773 0.1386 0.0315 0.5295 0.0701 0.0966
441 543 414 317 393 469 299 351 460 300
16 Landline Services 0.0126 0.06 0.09351 0.0995 -0.0471 0.03451 0.01011 -0.0768 -0.1321 -0.071
0.7919 0.1627 0.0573 0.0769 0.3514 0.4559 0.8619 0.1512 0.0045 0.22
441 543 414 317 393 469 299 351 460 300
17 Wireless Services 0.10128 0.06866 0.08966 0.05062 0.0645 0.08022 -0.0453 0.00292 0.00357 0.04061
0.0335 0.11 0.0684 0.369 0.202 0.0827 0.4352 0.9565 0.9391 0.4835
441 543 414 317 393 469 299 351 460 300
18 Internet Services 0.27734 0.26475 0.26194 0.23929 -0.0063 -0.0147 0.01586 0.00041 -0.0109 0.11641
<.0001 <.0001 <.0001 <.0001 0.9008 0.7509 0.7848 0.9939 0.816 0.0439
441 543 414 317 393 469 299 351 460 300
Sustainability of Patent-based Competitive Advantage 56
11 12 13 14 15 16 17
10 Assets/ Employees7
11 Intangibles/ All Assets0
12 Intangibles/ All Assets1 0.69336
<.0001
238
13 Intangibles/ All Assets7 0.23217 0.46054
0.0032 <.0001
159 217
14 Long-Term Debt/ Assets4 -0.0333 -0.079 -0.0572
0.6499 0.199 0.3605
188 266 258
15 Has Patents 0.03963 0.04928 0.13374 -0.2338
0.5037 0.3311 0.022 <.0001
287 391 293 359
16 Landline (Wired) Services -0.0595 -0.0156 0.01234 0.07484 -0.1141
0.3149 0.759 0.8334 0.1571 0.0049
287 391 293 359 606
17 Wireless Services 0.10435 0.0816 -0.0166 -0.0468 0.03214 -0.2642
0.0776 0.1072 0.7772 0.3766 0.4297 <.0001
287 391 293 359 606 606
18 Internet Services 0.02119 0.08011 0.14041 0.06953 0.16305 0.16078 0.06354
0.7208 0.1137 0.0162 0.1887 <.0001 <.0001 0.1182
287 391 293 359 606 606 606
Sustainability of Patent-based Competitive Advantage 57
Exhibit 1c
Means for Patent Scores
N Mean Std Dev Minimum Maximum
1 Return on Sales3 438 -0.11279 3.53648 -69.4362 0.72962
2 Return on Sales5 386 0.11009 1.02957 -13.0874 0.69196
3 Return on Sales7 318 -0.01984 3.07646 -51.8492 0.66735
4 Backward Citation Score be-fore Acquisition (7-year aver-age)
286 33.5651 16.6928 0.05 126.9924
5 Backward Citation Score of 4th Year after Acquisition
155 39.6325 36.0023 0.05 321.3153
6 Backward Citation Score after Acquisition (7-year average)
303 38.5932 31.2296 0.05 269.6336
7 LogAssets3 443 3.36328 1.12241 -0.23062 6.0368
8 LogAssets5 390 3.29129 1.18478 -1.55284 5.82822
9 LogAssets7 317 3.4574 1.15493 -0.30103 5.90055
10 Productivity3 401 0.60186 2.26034 0.00362 29.7416
11 Productivity5 354 0.68751 2.33556 0.01356 29.34458
12 Assets/ Employees5 355 2.80529 12.3496 0.0246 140.146
13 Assets/ Employees7 300 3.16357 11.2369 0.05033 108.7581
14 R&D Expense/ Sales7 98 0.13455 0.61921 0.00108 6.10684
15 Patents in Year5/ R&D Costs5 93 2.95391 17.1839 0 140
16 Landline (Wired) Services 606 0.72277 0.448 0 1
17 Wireless Services 606 0.49505 0.50039 0 1
18 Internet Services 606 0.19142 0.39374 0 1
Sustainability of Patent-based Competitive Advantage 58
Exhibit 1d
Correlations for Patent Scores
1 2 3 4 5 6 7 8 9
1 Return on Sales3
2 Return on Sales5 0.53619
<.0001
372
3 Return on Sales7 0.09306 0.26441
0.1042 <.0001
306 315
4 Backward Citation Score before Acquisition (7-year average)
0.15333 0.16301 0.16095
0.0223 0.0205 0.0314
222 202 179
5 Backward Citation Score of 4th Year after Acquisition
0.05538 0.08951 0.06353 0.1746
0.5173 0.3169 0.5116 0.0436
139 127 109 134
6 Backward Citation Score after Acquisition (7-year average)
-0.0117 0.04738 0.09574 0.31769 0.6513
0.8545 0.4746 0.1808 <.0001 <.0001
249 230 197 229 155
Sustainability of Patent-based Competitive Advantage 59
7 LogAssets3 0.1638 0.25117 0.14787 0.1108 -0.1113 -0.0448
0.0014 <.0001 0.0141 0.0966 0.2006 0.4845
380 331 275 226 134 246
8 LogAssets5 0.18422 0.27505 0.1827 0.1538 -0.1306 0.03499 0.83665
0.0004 <.0001 0.0012 0.0289 0.1465 0.6 <.0001
372 383 313 202 125 227 335
9 LogAssets7 0.17688 0.26787 0.21482 0.24705 -0.1585 0.01782 0.79324 0.95336
0.002 <.0001 0.0001 0.0009 0.1047 0.8058 <.0001 <.0001
302 311 314 178 106 193 273 313
10 Productivity3 0.0322 0.06396 0.03446 0.02883 0.07039 -0.0426 0.06213 0.02077 0.06575
0.5203 0.2388 0.5658 0.6801 0.4262 0.5239 0.247 0.7019 0.2746
401 341 280 207 130 226 349 342 278
11 Productivity5 0.03539 0.0722 0.03447 0.12776 0.04947 -0.0491 0.07092 0.02852 0.06258
0.5105 0.1753 0.5595 0.079 0.59 0.4772 0.2153 0.5928 0.2898
348 354 289 190 121 212 307 354 288
12 Assets/ Employees5 0.02694 0.04472 0.02972 0.02748 0.31964 0.14467 0.07562 0.03263 0.07473
0.6165 0.4015 0.6148 0.7066 0.0004 0.0353 0.1856 0.54 0.206
348 354 289 190 121 212 308 355 288
13 Assets/ Employees7 0.02899 0.03498 0.0602 0.09393 -0.0694 0.04287 -0.0227 0.00848 0.01631
0.6236 0.5482 0.2995 0.2231 0.4882 0.5634 0.7169 0.8843 0.7784
289 297 299 170 102 184 257 297 300
14 R&D Expense/ Sales7 -0.1186 -0.845 -0.9046 -0.2351 0.03235 -0.163 -0.195 -0.1705 -0.2006
0.2474 <.0001 <.0001 0.0335 0.8254 0.1459 0.0738 0.0932 0.0477
97 98 98 82 49 81 85 98 98
Sustainability of Patent-based Competitive Advantage 60
15 Patents in Year5/ R&D Costs5
0.01849 0.00823 -0.0188 -0.1482 -0.065 -0.0097 0.02036 -0.2187 -0.1956
0.8603 0.9376 0.8655 0.176 0.6371 0.9277 0.8605 0.0352 0.0746
93 93 84 85 55 90 77 93 84
16 Landline (Wired) Services 0.10699 0.10427 0.01318 0.18777 0.0551 -0.067 0.0859 0.06732 0.0995
0.0251 0.0406 0.8149 0.0014 0.4959 0.2448 0.0709 0.1846 0.0769
438 386 318 286 155 303 443 390 317
17 Wireless Services 0.06397 0.05034 0.06901 -0.1026 -0.1011 0.06144 0.03848 0.08385 0.05062
0.1814 0.3239 0.2197 0.0833 0.2105 0.2864 0.4191 0.0982 0.369
438 386 318 286 155 303 443 390 317
18 Internet Services -0.0738 0.03198 0.04795 0.16814 0.08041 0.13908 0.27494 0.2711 0.23929
0.1231 0.5311 0.3941 0.0044 0.3199 0.0154 <.0001 <.0001 <.0001
438 386 318 286 155 303 443 390 317
Sustainability of Patent-based Competitive Advantage 61
10 11 12 13 14 15 16 17
10 Productivity3
11 Productivity5 0.94111
<.0001
330
12 Assets/ Employees5 0.94561 0.94448
<.0001 <.0001
330 354
13 Assets/ Employees7 0.87831 0.89594 0.96236
<.0001 <.0001 <.0001
271 280 280
14 R&D Expense/ Sales7 -0.1915 -0.1935 0.04937 -0.038
0.063 0.0603 0.6347 0.7135
95 95 95 96
15 Patents in Year5/ R&D Costs5 0.00657 -0.1003 -0.1066 -0.0934 -0.1231
0.951 0.3442 0.3147 0.4039 0.2797
90 91 91 82 79
16 Landline (Wired) Services -0.0814 -0.0584 -0.1113 -0.071 0.02128 0.08928
0.1036 0.2729 0.0362 0.22 0.8353 0.3948
401 354 355 300 98 93
17 Wireless Services 0.04621 0.02323 0.03832 0.04061 0.05438 -0.1482 -0.2642
0.356 0.6631 0.4717 0.4835 0.5949 0.1562 <.0001
401 354 355 300 98 93 606
18 Internet Services -0.014 -0.0161 -0.0105 0.11641 -0.0496 0.13538 0.16078 0.06354
0.7795 0.7628 0.8433 0.0439 0.628 0.1957 <.0001 0.1182
401 354 355 300 98 93 606 606
Sustainability of Patent-based Competitive Advantage 62
Exhibit 2
Effect of Having Patents on EBITDA Divided by Sales (ROS)
1 2 3 4 5 6
ROS ROS ROS ROS ROS ROS
1 year after 2 years after 3 years after 4 years after 5 years after 7 years after
acquisition acquisition acquisition acquisition acquisition acquisition
Intercept -0.23989 -0.39686 0.00590 0.04195 0.07382 -0.05142
0.14066 0.13596 0.14697 0.05503 0.09286 0.08851
† ** NS NS NS NS
Having Patents 0.34759 0.52083 0.21385 0.10494 -0.14170 -0.00093
0.10065 0.11060 0.10578 0.04770 0.07139 0.06965
** *** * * * NS
R&D/ Sales -1.69775a -2.12316b -1.26252c -0.68853d -0.80081e -1.00328f
0.18353 0.42484 0.21761 0.13611 0.18544 0.16384
*** *** *** *** *** ***
Long-Term Debt/ Total Assets 0.27663 0.51471 0.24991 -- -- --
0.16278 0.22481 0.13409
† * †
Assets per Employee -0.00003 -0.00009 -0.00015 0.07534 -- --
0.00095 0.00077 0.00079 0.01026
NS NS NS ***
Sustainability of Patent-based Competitive Advantage 63
ROS ROS ROS ROS ROS ROS
1 year after 2 years after 3 years after 4 years after 5 years after 7 years after
acquisition acquisition acquisition acquisition acquisition acquisition
LogAssets -- -- -- -- 0.09662 0.07222
0.02330 0.01729
*** ***
Landline (Wired) Services -0.00160 0.10358 -0.17599 -0.01936 -0.13901 0.04913
0.08695 0.10218 0.09302 0.03687 0.05420 0.04599
NS NS † NS * NS
Wireless Services 0.05513 -- 0.10484 -- -- -0.04852
0.07366
0.07822
0.04054
NS
NS
NS
Internet Services 0.06859 -- 0.10781 -0.00848 0.03466 -0.05944
0.09859
0.08688 0.03978 0.06236 0.05069
NS
NS NS NS NS
Adjusted R2 0.4831 0.4564 0.3886 0.4673 0.4177 0.5326
Observations 108 68 85 106 108 96
*** < 0.001 ** 0.01 * 0.05 † 0.10
Sustainability of Patent-based Competitive Advantage 64
Exhibit 3
Effect of Patent Scores on EBITDA Divided by Sales (ROS)
1 2 3 4 5 6
ROS ROS ROS ROS ROS ROS
1 year after 3 years after 4 years after 5 years after 7 years after 7 years after
acquisition acquisition acquisition acquisition acquisition acquisition
Intercept -0.27700 0.06360 -0.04893 -0.29845 -0.32998 -0.18730
0.20642 0.13858 0.07296 0.06628 0.11559 0.09177
NS NS NS *** ** **
Backward Patent Scores 0.00990a 0.00117b 0.00218c 0.00152d 0.00271e 0.00134f
0.0039 0.00052 0.00078 0.00034 0.00113 0.00047
* * † *** * **
R&D Expense / Sales -1.27817 -0.70849 -0.37648 -- -0.64266 -0.72204
0.23563 0.16295 0.15613
0.28723 0.28218
*** *** *
* *
Patents/ R&D Expense -- -- -- 0.00131 -- --
0.00037
†
Assets per Employee -- -- 0.06958 -- 0.07749 --
0.01599
0.02788
***
**
Sustainability of Patent-based Competitive Advantage 65
ROS ROS ROS ROS ROS ROS
1 year after 3 years after 4 years after 5 years after 7 years after 7 years after
acquisition acquisition acquisition acquisition acquisition acquisition
LogAssets 0.01148 0.05560 0.05583 0.10619 0.08786 0.08524
0.04123 0.02827 0.01559 0.01604 0.02202 0.01914
NS † ** *** ** ***
Long-term debt/ Total Assets -- -- -- -0.10217 -- --
0.11579
NS
Diversification 0.55251 -- -- -- -- --
0.28301
†
Wired Services -- -0.16929 -0.10471 -- 0.10756 --
0.08228 0.04023
0.06126
* *
†
Wireless Services -- -- -0.04638 -- -0.06478 --
0.03485
0.05141
NS
NS
Internet Services -- -- -0.02132 -- -0.14816 --
0.04092
0.06021
NS
*
Sustainability of Patent-based Competitive Advantage 66
Adjusted R2 0.4386 0.4851 0.5282 0.5638 0.4806 0.5033
Observations 54 50 80 44 79 47
*** <0.0001 ** 0.01 * 0.05 † 0.10
a Year0 patent scores
b Year3 patent scores
c 4-year average patent scores
d Year4 patent scores
e 7-year average patent scores f Year4 patent scores
Sustainability of Patent-based Competitive Advantage 67
Exhibit 4
Effect of Changes in Patent Scores on Post-Acquisition Changes in Return on Sales
1 2 3 4 5
Year1 Year2 Year3 Year4 Year6
changes changes changes changes changes
in ROS in ROS in ROS in ROS in ROS
Intercept -0.19149 -0.61993
-0.93734 -1.09647 -0.37127
0.43343 0.62941 0.51811 0.84037 0.64965
NS NS † NS NS
Changes in 1.21333a 1.06224b 1.06288c 0.63334d -0.03819e
Patent Scores 0.11227 0.15819 0.13478 0.17854 0.00913
*** *** *** ** **
Changes in -0.00030 -- -- -- --
R&D Expense/ Assets 0.00892
NS
Changes in -- 0.18535
-0.21938 0.04639 0.27095
R&D Expense/ Patents
0.19484 0.18597 0.41801 0.34546
NS NS NS NS
LogAssets -0.01309 0.11701 0.23445 0.26811 0.12916
0.11017 0.15231 0.13039 0.20509 0.15897
NS NS † NS NS
Adjusted R2 0.7647 0.4856 0.5866 0.1674 0.3223
Observations 37 46 43 49 43
*** <0.0001 ** 0.01 * 0.05
a Difference of year1 score change from year0 score divided by year0 score
b Difference of year2 score change from year1 score divided by year1 score c Difference of year3 score change from year2 score divided by year2 score d Difference of year4 score change from year3 score divided by year3 score e Difference of year6 score change from year5 score divided by year5 score