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Uniqueness and Collection Overlap in Academic Libraries
Charleston ConferenceNovember 6, 2009
Michael Levine-ClarkSara Holladay
Margaret M. Jobe
Introduction
• Are academic libraries building diverse collections?
• Using automated tools such as Spectra Dimension we can:
– compare uniqueness of holdings in pre-established consortia vs. unconnected groupings of similar schools
– analyze percentage of uniqueness in a subject-based analysis
Brief Literature Review: Unique Titles and Duplication
• 72 ARL Libraries - Perrault (1995)
– Decline in the acquisitions rate for new imprints, 1985-1989
– Decrease in the number of unique titles
– Increased concentration of core materials
– Conclusion: collective resource base of research libraries in decline
Brief Literature Review Cont.
• Triangle Research Libraries Network - Armstrong & Nardini (2000)
– 50 year history of cooperative collection building
– 89% of titles held by two or more libraries
– Duplication generally not caused by approval plans
• OhioLink - Kairis (2003)
– High level of duplication in the Central Catalog.
• Academic Libraries- Nardini et al (1996)
– Greater collection overlap in larger libraries.
– Significant collection overlap in history.
The Data
• Spectra Dimension
– Holdings and Use Data for 45 libraries
• Monographs
• Start date of 1999
• End date varies (2006-2008)
• Data from existing consortia compared to groups of similar libraries
Two Liberal Arts Consortia
Institution Titles Unique Titles % Unique (within group)
Unique Titles as % of Local Collection
Liberal Arts 1 64,789 30,255 24.94% 46.70%
Liberal Arts 2 56,475 27,698 22.83% 49.04%
Liberal Arts 3 52,969 21,813 17.98% 41.18%
Overlap 41,553 34.25%
Institution Titles Unique Titles % Unique (within group)
Unique Titles as % of Local Collection
Liberal Arts 4 70,059 43,636 28.22% 62.28%
Liberal Arts 5 56,558 30,724 19.87% 54.32%
Liberal Arts 6 75,824 37,194 24.06% 49.05%
Overlap 43,055 27.85%
Other Liberal Arts ComparisonsInstitution Titles Unique Titles % Unique
(within group)Unique Titles as % of Local Collection
Liberal Arts 1 64,789 34,297 22.42% 52.94%
Liberal Arts 6 75,824 40,535 26.49% 53.46%
Liberal Arts 7 67,250 32,579 21.29% 48.44%
Overlap 45,548 29.79%
Institution Titles Unique Titles % Unique (within group)
Unique Titles as % of Local Collection
Liberal Arts 1 64,789 32,519 21.65% 50.19%
Liberal Arts 4 70,059 37,768 25.14% 53.91%
Liberal Arts 7 67,250 37,211 24.77% 55.33%
Overlap 42,730 28.44%
Liberal Arts Observations
• The unconnected groups do about as well as the two consortia:– Overlap
• Consortium A: 34.25%• Consortium B: 27.85%• Liberal Arts Group A: 29.79%• Liberal Arts Group B: 28.44%
– Unique Titles• Consortium A: 17.98%-24.94% (average 21.92%)• Consortium B: 19.87%-28.22% (average 24.05%)• Liberal Arts Group A: 21.29%-26.49% (average 23.40%)• Liberal Arts Group B: 21.65%-25.14% (average 23.85%)
Liberal Arts Observations
• The unconnected groups do about as well as the two consortia:
– Unique Titles as % of Collections
• Consortium A: 41.18%-49.04% (average 45.64%)
• Consortium B: 49.05%-62.28% (average 55.22%)
• Liberal Arts Group A: 48.44%-53.46% (average 51.61%)
• Liberal Arts Group B: 50.19%-55.33% (average 52.48%)
Liberal Arts Observations
• Size of group may matter– Consortium A: 121,319 titles / 34.25% overlap
– Consortium B: 154,609 titles / 27.85% overlap
– Liberal Arts Group A: 152,959 titles / 29.79% overlap
– Liberal Arts Group B: 150,228 titles / 28.44% overlap
• Size of institution may not
• Cooperation may not
Groups in a Larger ConsortiumInstitution Titles Unique Titles % Unique
(within group)Unique Titles as % of Local Collection
Doctoral 1 208,248 34,132 7.21% 16.39%
ARL 3 348,181 124,350 26.25% 35.71%
ARL 4 278,650 70,848 14.96% 25.43%
Overlap 244,355 51.59%
Institution Titles Unique Titles % Unique (within group)
Unique Titles as % of Local Collection
Doctoral 1 208,248 104,993 32.55% 50.42%
Doctoral 3 129,914 47,936 14.86% 36.90%
Doctoral 4 133,645 55,188 17.11% 41.29%
Overlap 114,436 35.48%
Groups in a Larger ConsortiumInstitution Titles Unique Titles % Unique
(within group)Unique Titles as % of Local Collection
Doctoral 3 129,914 59,067 22.18% 45.47%
Doctoral 4 133,645 71,692 26.92% 53.64%
Doctoral 5 116,799 48,800 18.32% 41.78%
Overlap 86,801 32.59%
Institution Titles Unique Titles % Unique (within group)
Unique Titles as % of Local Collection
Liberal Arts 7 67,250 33,809 18.71% 50.27%
Masters 1 55,848 24,688 13.66% 44.21%
Doctoral 5 116,799 72,644 40.20% 62.20%
Overlap 49,582 27.44%
Other GroupsInstitution Titles Unique Titles % Unique
(within group)Unique Titles as % of Local Collection
ARL 2 359,826 172,579 28.19% 47.96%
ARL 3 348,181 104,931 17.14% 30.14%
ARL 4 278,650 69,076 11.28% 24.79%
Overlap 265,546 43.38%
Institution Titles Unique Titles % Unique (within group)
Unique Titles as % of Local Collection
ARL 5 196,144 83,469 21.76% 42.55%
Doctoral 1 208,248 80,633 21.02% 38.72%
Doctoral 2 172,541 72,496 18.90% 42.02%
Overlap 146,966 38.32%
Larger Collections = Greater Overlap
• Consortium C (1): 51.59% (473,685 titles)
• Consortium C (2): 35.48% (322,553)
• Consortium C (3): 32.59% (266,360)
• Consortium C (4): 27.44% (180,723)
• ARL Group: 43.38% (612,132)
• ARL/Doctoral Group: 38.32% (383,564)
Larger Collections = Greater Overlap
• Consortium C (1): 51.59% (range: 139,933)
• Consortium C (2): 35.48% (78,334)
• Consortium C (3): 32.59% (16,846)
• Consortium C (4): 27.44% (60,951)
• ARL Group: 43.38% (81,176)
• ARL/Doctoral Group: 38.32% (35,707)
(Range is difference between largest and smallest collections)
Unique Titles
• Consortium C (1): 7.21%-26.25% - Avg 16.14% (473,685 titles)
• Consortium C (2): 14.86%-32.55% - Avg 21.51% (322,553)
• Consortium C (3): 18.32%-26.92% - Avg 22.47% (266,360)
• Consortium C (4): 13.66%-40.20% - Avg 24.19% (180,723)
• ARL Group: 11.28%-28.19% - Avg 18.87% (612,132)• ARL/Doctoral Group: 18.90%-21.76% - Avg 20.56%
(383,564)
Unique Titles
• Consortium C (1): 7.21%-26.25% - Avg 16.14% (Range: 139,933)
• Consortium C (2): 14.86%-32.55% - Avg 21.51% (78,334)
• Consortium C (3): 18.32%-26.92% - Avg 22.47% (16,846)
• Consortium C (4): 13.66%-40.20% - avg 24.19% (60,951)
• ARL Group: 11.28%-28.19% - Avg 18.87% (81,176)• ARL/Doctoral Group: 18.90%-21.76% - Avg 20.56%
(35,707)
Size matters
• In 5/6 cases, largest collection is most unique
(exception: range=12,104, difference=.74%)
• In all cases, smallest is least unique
• In 5/6 cases, largest collection has most unique titles as % of local collection
• In 5/6 cases, smallest collection has fewest unique titles as % of local collection
Two Liberal Arts Consortia –Subject Analysis (Am Hist – E)
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Liberal Arts 1 2,921 25.69% Unique to Base 37.69%
Liberal Arts 2 1,393 29.24% 8.91% Base plus one 43.55%
Liberal Arts 3 2,494 51.73% 19.34% Base plus two 18.76%
Overlap 46.06%
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Liberal Arts 5 2,934 30.28% Unique to Base 52.42%
Liberal Arts 4 2,360 22.63% 22.78% Base plus one 34.63%
Liberal Arts 6 2,101 37.90% 8.86% Base plus two 12.95%
Overlap 38.08%
Other Liberal Arts Comparisons –Subject Analysis (Am Hist – E)
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Liberal Arts 1 2,921 26.18% Unique to Base 47.55%
Liberal Arts 6 2,101 34.13% 13.18% Base plus one 37.52%
Liberal Arts 7 2,656 33.24% 24.13% Base plus two 14.93%
Overlap 36.51%
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Liberal Arts 1 2,921 25.24% Unique to Base 47.62%
Liberal Arts 4 2,360 33.82% 16.39% Base plus one 37.69%
Liberal Arts 7 2,656 33.24% 22.07% Base plus two 14.69%
Overlap 36.30%
Liberal Arts Observations –American History (E): Uniqueness
• Unique to Base Library
– Consortium A: 37.69% (27.42%, 33.24%)
– Consortium B: 52.42% (21.42%, 49.03%)
– Liberal Arts Group A: 47.55% (33.27%, 48.19%)
– Liberal Arts Group B: 47.62% (38.26%, 45.78%)
(Numbers in parentheses are the values if other libraries in the group are the base)
Liberal Arts Observations –American History (E): Overlap
• Overlap– Consortium A: 46.06%
– Consortium B: 38.08%
– Liberal Arts Group A: 36.51%
– Liberal Arts Group B: 36.30%
• Held by Base Library and Two Others:– Consortium A: 18.76% (21.97%, 39.34%
– Consortium B: 12.95% (16.10%, 18.09%)
– Liberal Arts Group A: 14.93% (16.42%, 20.75%)
– Liberal Arts Group B: 14.69% (16.15%, 18.18%)
Groups in A Larger Consortium –Subject Analysis (Am Hist – E)
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
ARL 3 8,535 11.70% Unique to Base 13.98%
ARL 4 7,516 75.92% 7.78% Base plus one 27.62%
Doctoral 1 6,716 68.51% 6.14% Base plus two 58.41%
Overlap 74.38%
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Doctoral 1 6,716 6.14% Unique to Base 9.32%
ARL 3 8,535 87.06% 11.70% Base plus one 16.45%
ARL 4 7,516 77.84% 7.78% Base plus two 74.23%
Overlap 74.38%
Groups in A Larger Consortium –Subject Analysis (Am Hist – E)
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Doctoral 1 6,716 25.88% Unique to Base 35.82%
Doctoral 3 3,485 36.42% 7.89% Base plus one 41.80%
Doctoral 4 5,215 50.13% 16.59% Base plus two 22.38%
Overlap 49.64%
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Doctoral 4 5,215 34.74% Unique to Base 51.39%
Doctoral 3 3,485 34.67% 17.19% Base plus one 35.09%
Doctoral 5 2,605 27.46% 10.66% Base plus two 13.52%
Overlap 37.41%
Groups in A Larger Consortium –Subject Analysis (Am Hist – E)
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Doctoral 5 2,605 27.69% Unique to Base 50.83%
Liberal Arts 7 2,656 40.42% 27.19% Base plus one 35.55%
Masters 1 1,459 22.38% 11.98% Base plus two 13.63%
Overlap 33.14%
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Liberal Arts 7 2,656 27.19% Unique to Base 48.95%
Doctoral 5 2,605 39.65% 27.69% Base plus one 37.69%
Masters 1 1,459 24.77% 11.98% Base plus two 13.37%
Overlap 33.14%
Other Groups –Subject Analysis (Am Hist – E)
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
ARL 2 8,090 14.46% Unique to Base 20.01%
ARL 3 8,535 76.98% 8.11% Base plus one 17.19%
ARL 4 7,516 65.80% 7.09% Base plus two 62.79%
Overlap 70.34%
Institution Titles Overlap (with base)
% Unique (within group)
Overlap
Doctoral 1 6,716 14.08% Unique to Base 20.19%
ARL 5 5,643 60.99% 9.01% Base plus one 33.14%
Doctoral 2 6,448 65.49% 14.23% Base plus two 46.66%
Overlap 62.68%
American History Comparisons -Conclusions
• Research Libraries - not as unique as one would expect?
– Overlap:
• ARL/Doctoral Group (Consortium): 74.38%%
• Doctoral Groups (Consortium): 49.64%/37.41%
• Smallest Group: 33.14%
• ARL Group: 70.34%
• ARL/Doctoral Group: 62.68%
American History Comparisons -Conclusions
• Research Libraries - not as unique as one would expect?
– Base + Two:
• ARL/Doctoral Group (Consortium): 58.41%/74.23%
• Doctoral Groups (Consortium): 22.38%/13.52%
• Smallest Group: 13.63%/13.37%
• ARL Group: 62.79%
• ARL/Doctoral Group: 46.66%
American History Comparisons -Conclusions
• Research Libraries - not as unique as one would expect?
– Most Unique Collection:
• ARL/Doctoral Group (Consortium): 11.70%
• Doctoral Groups (Consortium): 25.88%/34.74%
• Smallest Group: 27.69%
• ARL Group: 14.46%
• ARL/Doctoral Group: 14.23%
Conclusion
• Consortial agreements do not seem to lead to decreased overlap.
• Larger libraries duplicate each other more than do smaller libraries.
Future directions
• Detailed subject analysis.
• Comparative analysis of use.
• Survey of libraries contributing holdings information to Spectra Dimension about collection development patterns.
• Overview of local programs/curricula.
References
• Kim Armstrong and Bob Nardini, “Making the Common Uncommon? Examining ConsortialApproval Plan Cooperation,” Collection Management 24, no. 1-2 (2000):87-105.
• Rob Kairis, “Consortium Level Collection Development: A Duplication Study of the OhioLINK Central Catalog,” Library Collections, Acquistions, & Technical Services 27 (2003):317-326.
References Cont.
• Robert F. Nardini, Charles M. Getchell, Jr., and Thomas E. Cheever, C. M. Getchell, “Approval plan overlap: A study of four libraries,” Acquisitions Librarian 16 (1996): 75-97.
• Anna H. Perrault, “The Changing Print Resource Base of Academic Libraries in the United States,” Journal of Education for Library and Information Science, 36 (Fall 1995):295-308.
Michael Levine-Clark
michael.levine-clark@du.edu
Sara Holladay
sara.holladay@gmail.com
Margaret M. Jobe
margaret.jobe@colorado.edu