EUCS test–retest reliability in representational model decision support systems

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Research EUCS test–retest reliability in representational model decision support systems Roger McHaney a,* , Ross Hightower b , Doug White 1,c a Department of Management, College of Business Administration, Kansas State University, Manhattan, KS 66506, USA b College of Business Administration, University of Central Florida, P.O. Box 161991, Orlando, FL 32816-1991, USA c University of Northern Colorado, College of Business Administration, Kepner Hall, Geeley, CO 80639, USA Received 6 February 1998; accepted 28 January 1999 Abstract A test–retest reliability study of an end-user computing satisfaction instrument was conducted. The instrument was distributed to real-world representational decision support system users through a mail survey. One month later, follow-up surveys were mailed asking the original respondents to again evaluate the same system. The data sets were compared and suggest that the instrument is internally consistent and stable when applied to its users. # 1999 Elsevier Science B.V. All rights reserved. Keywords: End-user computing satisfaction (EUCS); Computer simulation; Satisfaction 1. Introduction The proliferation of information technology (IT) and its importance in effective managerial decision making has created a greater need for valid and reliable evaluative instruments. While a number of these instruments have been developed [7, 20] and validated [13, 17, 18, 29, 37] using various techniques, caution must be used in its application to specific IT areas outside those previously tested [9]. In addition, many reliability tests were performed on relatively small student groups; the members may differ from their real-world counterparts [6, 19]. The present article reports on the validity and test–retest reliability of an end-user computing satisfaction instrument when applied to real-world users of representational model decision support systems (DSS) [1]. Researchers wishing to conduct studies assessing success or failure of various information system applications are faced with a dizzying array of choices [3]. Delone and McLean [8] have organized over 180 articles according to six dimensions of success– system quality, information quality, use, user satisfac- tion, individual impact and organizational impact. Many of these studies have provided instruments, measures, or techniques intended to measure or pre- dict information system success. Much of the work in this area has been in response to the lack of a widely accepted dependent variable for the measurement of IS success. The identification of a satisfaction measure both plagues and motivates IS researchers. Long ago, Keen [23] listed issues of importance in the field of MIS and included the identification of a dependent variable. Information & Management 36 (1999) 109–119 *Corresponding author. Fax: +1-913-532-7479; e-mail: [email protected] 1 E-mail: [email protected] 0378-7206/99/$ – see front matter # 1999 Elsevier Science B.V. All rights reserved. PII:S-0378-7206(99)00010-5

Transcript of EUCS test–retest reliability in representational model decision support systems

Page 1: EUCS test–retest reliability in representational model decision support systems

Research

EUCS test±retest reliability in representationalmodel decision support systems

Roger McHaneya,*, Ross Hightowerb, Doug White1,c

aDepartment of Management, College of Business Administration, Kansas State University, Manhattan, KS 66506, USAbCollege of Business Administration, University of Central Florida, P.O. Box 161991, Orlando, FL 32816-1991, USA

cUniversity of Northern Colorado, College of Business Administration, Kepner Hall, Geeley, CO 80639, USA

Received 6 February 1998; accepted 28 January 1999

Abstract

A test±retest reliability study of an end-user computing satisfaction instrument was conducted. The instrument was distributed

to real-world representational decision support system users through a mail survey. One month later, follow-up surveys were

mailed asking the original respondents to again evaluate the same system. The data sets were compared and suggest that the

instrument is internally consistent and stable when applied to its users. # 1999 Elsevier Science B.V. All rights reserved.

Keywords: End-user computing satisfaction (EUCS); Computer simulation; Satisfaction

1. Introduction

The proliferation of information technology (IT)

and its importance in effective managerial decision

making has created a greater need for valid and

reliable evaluative instruments. While a number of

these instruments have been developed [7, 20] and

validated [13, 17, 18, 29, 37] using various techniques,

caution must be used in its application to speci®c IT

areas outside those previously tested [9]. In addition,

many reliability tests were performed on relatively

small student groups; the members may differ from

their real-world counterparts [6, 19]. The present

article reports on the validity and test±retest reliability

of an end-user computing satisfaction instrument

when applied to real-world users of representational

model decision support systems (DSS) [1].

Researchers wishing to conduct studies assessing

success or failure of various information system

applications are faced with a dizzying array of choices

[3]. Delone and McLean [8] have organized over 180

articles according to six dimensions of success±

system quality, information quality, use, user satisfac-

tion, individual impact and organizational impact.

Many of these studies have provided instruments,

measures, or techniques intended to measure or pre-

dict information system success. Much of the work

in this area has been in response to the lack of a widely

accepted dependent variable for the measurement

of IS success.

The identi®cation of a satisfaction measure both

plagues and motivates IS researchers. Long ago, Keen

[23] listed issues of importance in the ®eld of MIS and

included the identi®cation of a dependent variable.

Information & Management 36 (1999) 109±119

*Corresponding author. Fax: +1-913-532-7479; e-mail:

[email protected]: [email protected]

0378-7206/99/$ ± see front matter # 1999 Elsevier Science B.V. All rights reserved.

PII: S - 0 3 7 8 - 7 2 0 6 ( 9 9 ) 0 0 0 1 0 - 5

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Delone and McLean more recently echoed the impor-

tance of this sentiment by stating, `̀ . . .if information

systems research is to make a contribution to the world

of practice, a well-de®ned outcome measure (or mea-

sures) is essential. . .without a well-de®ned dependent

variable, much of I/S research is purely speculative.''

Without a dependent variable, measurable by reli-

able instruments [21, 34], a meaningful comparison of

competing software packages, implementation

approaches, system attributes, and software features

becomes impossible. In spite of these problems, pro-

gress toward the identi®cation of a universal, depen-

dent IS success variable has been made. Yet, no single

standard has gained widespread acceptance in the IS

research community. Researchers have operationa-

lized dependent variables according to various criteria.

Delone and McLean suggested researchers might

eventually develop a single comprehensive instrument

to account for all dimensions of success. Until such an

instrument is developed, researchers studying a spe-

ci®c instance of information technology must spend

time selecting and validating an appropriate measure.

Each potential surrogate for success must be assessed.

The level at which the output of an IS will be measured

must be determined, relevant aspects of a system must

be determined and researchers' beliefs regarding

selection of an appropriate surrogate for success

require consideration.

After a choice is made, the researcher must face the

possibility that the instrument may not prove ideal, so

an assessment of the appropriateness of the selected

measure must be made. This means taking extra care

to demonstrate the validity and reliability of the

instrument used in the new context.

Although a comprehensive, standard IS instrument

for success does not yet exist, several very respectable

measures are presently available and in use. Among

these is the Doll and Torkzadeh [9] instrument for

measuring end-user computing satisfaction (EUCS).

This consists of two components: ease of use, and

information product. The information product com-

ponent is operationalized through measures of con-

tent, accuracy, format and timeliness [2]. These four

constructs, together with the ease of use variable,

comprise an instrument for end-user computing satis-

faction. This instrument is speci®cally designed to

work within the current end-user computing environ-

ment consistent with current trends [30].

Prior reliability and validation tests of the EUCS

instrument include the original development of the

instrument by Doll and Torkzadeh. This study indi-

cated adequate reliability and validity across a variety

of applications in various industries. In a follow-up

study, Torkzadeh and Doll used the responses from

forty-one M.B.A. student students familiar with var-

ious applications to test short-term (2 hour) and long-

term stability of the instrument (2 weeks) with test±

retest administrations. The results indicated that the

instrument is internally consistent and stable. Hen-

drickson, et al. further extended the long-term (2

weeks) test-retest reliability of the instrument in a

single public institution where mainframe- and perso-

nal computer-based applications were considered.

This study investigated the instrument at two points

in time separated by two years. The initial test±retest

samples included 32 mainframe and 35 PC users. The

second test±retest sample relied on 22 mainframe and

22 PC users. Doll et al. [10] performed a con®rmatory

factor analysis based on a sample of 409 respondents

from a variety of ®rms and applications.

Prior tests of EUCS have been encouraging but

suffer from one or more limitations. Tests have either

used student groups or groups of users within speci®c

®rms. Students may not be good surrogates for real-

world users and results from a single organization may

not be generalizable [22]. In addition, most published

studies have concentrated on either reliability or

validity (e.g. Refs. [16, 26]), not both. This study

addresses these limitations by examining the reliabil-

ity and validity of EUCS using a single sample drawn

from a population using real-world systems in a wide

range of ®rms.

2. Testing instruments

2.1. Reliability of instruments

An intuitive approach to estimating the reliability of

an instrument is to assess the repeatability or consis-

tency of collected measurements. A simple method of

putting this idea into practice is to employ the test -

retest method. When using this technique, a group of

subjects is tested twice using the same measure. The

two sets of scores are correlated and the correlation

coef®cient is used as an estimate of the reliability of

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the measurement. This approach assumes the correla-

tion between the test, and the retest is due to the

underlying, unobservable true scores of the instrument

that have remained constant. The correlation is

expected to be less than perfect due to random mea-

surement errors that may have occurred. While this

assumption is considerably optimistic, a ®nding of a

strong correlation does support the premise that the

instrument is stable.

The test±retest technique has been widely used,

however, it does have shortcomings. If a person is

tested twice in a row using the same instrument, a bias

may emerge due to a carry-over effect. The act of

®lling out the questionnaire items in the test may

in¯uence the responses given in the retest. If the

interval of time between testings is too short, the

respondent may recall their replies and try to match

them rather than reassess the content of the questions.

This could lead to an in¯ation of the correlations. If the

time period between administrations is too long, the

respondent or the system under study may undergo

changes that in¯uence the response. In addition, the

respondents will have an opportunity to think of

aspects of the system they had not considered in the

original administration of the test. To minimize these

effects, Nunnally [28] suggests waiting for an interval

between two weeks and one month. He suggests that

this period of time should be suf®cient to keep mem-

ory from being a strong factor.

Beside recall and time, another consideration is

reactivity, which can de¯ate test±retest correlations

and indicate a falsely lower reliability. This phenom-

enon occurs when a person becomes sensitized to the

instrument and `learns' to respond in a way he or she

believes is expected.

2.2. Validity

The validity, or the extent to which an instrument

measures what it is intended to measure [4], may be

assessed in two ways; construct and convergent valid-

ity. Construct validity is the degree to which the

measures chosen are either true constructs, describing

the event of interest or merely artifacts of the meth-

odology itself. Two methods of assessing construct

validity are correlation analysis and con®rmatory

factor analysis. Correlation analysis is used to indicate

the degree of association between each item and the

total score of an instrument. A signi®cant correlation

indicates the presence of construct validity. A con-

®rmatory analysis procedure can be performed to

provide evidence that a set of latent variables exist

and that these account for covariances among a set of

observed variables. The a priori designation of these

factor patterns are tested against sample data to pro-

vide evidence of their psychometric stability.

3. Current study

3.1. Representational model decision support

systems

An early study by Alter breaks DSS model types

into seven general categories. These are based on the

degree to which the system outputs determine the

resulting decision. The research examines a particular

DSS type±representational models, speci®cally dis-

crete event computer simulation.

Computer simulation has become a popular deci-

sion support tool [11, 12, 14, 15]. Computerized

simulation dates back to the 1950s, when some of

the ®rst computer models were developed. Simulation

was time consuming and dif®cult to use because of the

slow hardware and software platforms available at the

time. Problem-solving was cumbersome and costly. In

the seventies and early eighties simulation started to

be used more often in organizational decision-making

settings. The introduction of the personal computer

and the proliferation of simulation software in the late

eighties and early nineties has put computer simula-

tion into the hands of more decision makers. Not only

did the number of users increase, but so did the variety

of available simulation software packages [33]. In the

1993 OR/MS Today Simulation Software Survey,

James Swain [35] reported that practitioners of OR/

MS were familiar with simulation and also discussed

more than ®fty discrete event simulation products.

Most modern simulation usage centers on its capabil-

ity [24, 25, 27, 32, 36].

3.2. Research methods

This study's population of interest was users of

representational DSS, speci®cally discrete-event com-

puter simulation. A list of potential candidates was

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developed, using the membership list of the Society

for Computer Simulation and a list of the recent

Winter Simulation Conference attendees. Five hun-

dred and three of these candidates were randomly

selected. First, a letter was sent to the candidates

asking for participation, then the survey package

was mailed. A reminder card was sent two weeks

later. Each candidate received two questionnaires, one

asking for a report on a successful simulation effort

and the second asking for a report on a less-than-

successful one.

One-hundred and ninety-eight responses were

returned. Of these, 123 were suitable for analysis.

Fourteen packets were returned unopened. Another

®fty-nine returns indicated that the respondent would

be unable to participate in the study. Of the 123 usable

responses, forty questionnaires were paired. In other

words, both successful and less-than-successful simu-

lations were reported by the same source. Therefore,

of the 503 packets sent out, 105 different individuals/

companies were represented in a total of 123 different

simulation projects. This makes the net response rate

of 105 out of 489, or 21.5%. The respondents worked

in a variety of ®elds, ranging from manufacturing,

health, government, service, computer, and consult-

ing. The projects range from simple predictive models

to complex manufacturing systems.

As recommended by Nunnally [28], after receiving

an initial response, the follow-up survey was mailed

one month later, to prevent carry-over and memory

effects. The follow-up survey provided information

about the system described in the initial response and

asked for several additional pieces of information. The

set of EUCS questions were included among them.

Seventy-four usable responses were received in this

follow-up survey, making the response rate of 74 out

of 105, or 70%.

3.3. Reliability

3.3.1. Alpha

Reliability or internal consistency of the EUCS

instrument was assessed using Cronbach's � [5] and

found to be 0.928 for the test data and 0.938 for the

retest data. Table 1 shows these results. This study's

� compares favorably with an overall � of 0.92

in the original study [9]. The subscale �s also

report satisfactory values ranging from 0.797 to

0.929 for the test data and from 0.702 to 0.911 for

the retest data.

3.3.2. Correlation results

Correlation coef®cients between the components of

the end-user computing satisfaction instrument in the

test and retest administrations were computed. In the

individual scale, the correlations were found to range

from 0.409 to 0.701. The values were seen to improve

in the subscales which ranged from 0.551 to 0.729.

The global measures of EUCS correlated at 0.760.

These results are shown in Table 2.

Table 1

Internal consistencyÐCronbach's �s

Variable Test data � Retest data �

Overall instrument 0.928 0.938

Subscales

Content 0.851 0.911

Accuracy 0.929 0.886

Format 0.839 0.781

Ease of use 0.887 0.871

Timeliness 0.797 0.702

Global score 0.866 0.871

Table 2

Correlation analysis

Variable Correlation (test±retest)

A1 0.553

A2 0.544

C1 0.586

C2 0.561

C3 0.580

C4 0.559

E1 0.701

E2 0.588

F1 0.578

F2 0.602

T1 0.503

T2 0.409

Subscales

Accuracy 0.572

Content 0.664

Ease of use 0.729

Format 0.684

Timeliness 0.551

Overall

Summary 0.760

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3.3.3. Paired T-tests

The paired T-test results are shown in Table 3. The

subjects' individual responses from the test data set are

paired with the corresponding response from the retest

data set. The resulting mean differences are reported

for the individual items, the subscales and the global

score. Results indicate signi®cant differences (p < 0.05)

only in the responses for item A2Ð`Satis®ed with

accuracy'. The accuracy subscale also demonstrates a

difference between the test and retest data (p < 0.08).

The overall T-test was not signi®cant (p < 0.15).

3.4. Validity

Two methods of assessing construct validity were

used: correlation analysis and con®rmatory factor

analysis. Table 4 lists the single item correlations,

all of which are signi®cant, ranging from 0.579 to

0.805 for the test data and from 0.647 to 0.803 for the

retest data. The subscale correlations are also signi®-

cant and range from 0.634 to 0.852 in the test data and

from 0.641 to 0.852 in the retest data. These correla-

tions support the premise that the instrument has

construct validity. Table 5 reports simple statistics

and correlations for each element of the instrument.

Table 3

Paired T-test results

Variable Mean

difference

SE T Probability

> |T |

C1 0.013 0.099 0.136 0.89

C2 ÿ0.054 0.105 ÿ0.514 0.61

C3 ÿ0.149 0.103 ÿ1.442 0.15

C4 ÿ0.135 0.106 ÿ1.275 0.21

A1 ÿ0.135 0.104 ÿ1.297 0.20

A2 ÿ0.230 0.113 ÿ2.031 0.05** a

F1 ÿ0.040 0.091 ÿ0.445 0.66

F2 ÿ0.135 0.099 ÿ1.369 0.18

E1 0.040 0.108 0.378 0.71

E2 ÿ0.054 0.120 ÿ0.450 0.65

T1 ÿ0.040 0.122 ÿ0.331 0.74

T2 ÿ0.162 0.114 ÿ1.424 0.16

Subscales

Accuracy ÿ0.365 0.202 ÿ1.803 0.08* b

Content ÿ0.324 0.320 ÿ1.014 0.31

Ease of use ÿ0.014 0.189 ÿ0.071 0.94

Format ÿ0.176 0.152 ÿ1.156 0.25

Timeliness ÿ0.203 0.193 ÿ1.048 0.30

Overall

Global ÿ1.081 0.737 ÿ1.468 0.15

a Signi®cant (p < 0.05).b Signi®cant (p < 0.10).

Table 4

EUCS instrument reliability analysis

Item Corrected item±total correlation � of entire instrument, if item or construct is deleted

test retest combined test retest combined

C1 0.81 0.80 0.81 0.93 0.93 0.92

C2 0.80 0.80 0.83 0.93 0.93 0.92

C3 0.74 0.73 0.73 0.93 0.93 0.93

C4 0.77 0.68 0.72 0.93 0.93 0.93

A1 0.70 0.71 0.72 0.93 0.93 0.93

A2 0.75 0.75 0.76 0.93 0.93 0.93

E1 0.66 0.69 0.70 0.93 0.93 0.93

E2 0.66 0.65 0.80 0.93 0.93 0.92

F1 0.63 0.73 0.64 0.93 0.93 0.93

F2 0.80 0.78 0.62 0.93 0.93 0.93

T1 0.58 0.65 0.57 0.93 0.93 0.93

T2 0.71 0.69 0.69 0.93 0.93 0.93

Subscales

Content 0.85 0.85 0.86 0.83 0.83 0.82

Accuracy 0.72 0.70 0.73 0.84 0.85 0.84

Ease of Use 0.63 0.64 0.60 0.85 0.86 0.86

Format 0.80 0.79 0.81 0.83 0.84 0.83

Timeliness 0.70 0.70 0.67 0.84 0.85 0.85

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To further support the premise that this instrument

has construct validity, a factor analysis procedure was

performed to con®rm its psychometric properties.

Doll and Torkzadeh originally proposed a ®ve scale

factor structure. In subsequent research, they recom-

mended a second-order factor structure. It was a single

factor called end-user computing satisfaction. The ®rst-

order structure matches the original factor structure of

Table 5

EUCS instrument correlation matrices and simple statistics (sample size � 148)

(a) Item correlations

C2 0.81

C3 0.65 0.67

C4 0.60 0.69 0.54

A1 0.58 0.68 0.47 0.62

A2 0.65 0.71 0.48 0.66 0.83

E1 0.56 0.51 0.56 0.36 0.42 0.45

E2 0.53 0.50 0.53 0.29 0.42 0.44 0.78

F1 0.62 0.65 0.64 0.53 0.50 0.50 0.49 0.44

F2 0.69 0.74 0.68 0.63 0.61 0.71 0.58 0.55 0.68

T1 0.53 0.45 0.43 0.49 0.43 0.46 0.30 0.40 0.44 0.40

T2 0.59 0.59 0.50 0.76 0.59 0.54 0.40 0.32 0.48 0.49 0.61

C1 C2 C3 C4 A1 A2 E1 E2 F1 F2 T1

(b) Subscale and overall instrument correlations

Accuracy 0.728

Ease of Use 0.588 0.479

Format 0.818 0.667 0.597

Timeliness 0.695 0.583 0.418 0.545

Overall EUCS 0.941 0.823 0.745 0.868 0.768

Content Accuracy Ease of use Format Timeliness

(c) Individual items: simple statistics

Item Mean Standard deviation

C1 3.83 0.93

C2 4.00 0.95

C3 3.75 0.96

C4 3.99 0.97

A1 4.04 0.95

A2 4.11 1.02

E1 3.34 1.19

E2 3.41 1.13

F1 3.82 0.85

F2 3.96 0.94

T1 3.94 1.05

T2 4.07 0.90

(d) Subscales: simple statistics

Factor Mean Standard deviation

Content 15.57 3.29

Accuracy 8.16 1.88

Format 7.78 1.64

Ease of use 6.75 2.19

Timeliness 8.01 1.75

Overall EUCS 46.26 9.05

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Content, Accuracy, Format, Ease of Use and Time-

liness. The exact form of the instrument used in this

study is illustrated in Fig. 1. The second-order model

was assessed using con®rmatory factor analysis with

the SAS proc CALIS and LISREL 8 [31]. The model

contains the a priori factor structure that was tested.

Table 6 presents the goodness of ®t indexes for this

study and compares them to the values reported by

Doll et al. [10]. The absolute indexes (GFI � 0.866,

AGFI � 0.762 and RMSR � 0.051) compare favor-

ably with the values reported by Doll et al., indicating

a good model-data ®t. The �2-statistic divided by the

degrees of freedom also indicates a reasonable ®t at

3.30 [38].

LISREL's maximum likelihood estimates of the

standardized parameter estimates are presented in

Fig. 1. EUCS model. Five ®rst-order factors. One second-order factor.

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Table 7 for the observed variables and Table 8 for the

latent variables.

Table 7 compares factor loadings, corresponding t-

values, and R2-values for this study with those

reported by Doll, et al. All items have signi®cant

loadings on their corresponding factors, indicating a

good construct validity. R2-values range from 0.48 to

0.89 providing evidence of acceptable reliability for

all individual items.

Table 8 provides standard structural coef®cients

and corresponding t-values as well as R2-values for

the latent variables. The standard structural coef®-

Table 6

Goodness-of-fit indexes

Current study Doll, Xia and Torkzadeh Study (1994)

�2 (df) 145.15 (44) 185.81 (50)

�2/df 3.30 3.72

Normed fit index (NFI) 0.899 0.940

Goodness-of-fit index (GFI) 0.866 0.929

Adjusted goodness of fit index (AGFI) 0.762 0.889

Root mean square residual (RMSR) 0.051 0.035

Table 7

Standardized parameter estimates and t values

Item Current study Doll, Xia, and Torkzadeh Study (1994)

factor loading R2 (reliability) factor loading R2 (reliability)

C1 0.855 (12.77) 0.73 0.826* a 0.68

C2 0.891 (13.66) 0.79 0.852 (20.36) 0.73

C3 0.758 (10.66) 0.58 0.725 (16.23) 0.53

C4 0.781 (11.14) 0.61 0.822 (19.32) 0.68

A1 0.883 (13.16) 0.78 0.868* a 0.76

A2 0.944 (14.61) 0.89 0.890 (20.47) 0.79

F1 0.757 (10.49) 0.57 0.780* a 0.61

F2 0.900 (13.34) 0.81 0.829 (17.89) 0.69

E1 0.915 (12.91) 0.84 0.848* a 0.72

E2 0.856 (10.66) 0.58 0.880 (16.71) 0.78

T1 0.690 (8.85) 0.48 0.720* a 0.52

T2 0.880 (11.72) 0.78 0.759 (13.10) 0.58

a Asterisk indicates a parameter ®xed at 1.0 in original solution. t values for item factor loadings are indicated in parentheses.

Table 8

Structural coefficients and t values

Item Current study Doll, Xia, and Torkzadeh Study (1994)

standard structure coefficient a R2 (reliability) standard structure coefficient a R2 (reliability)

Content 0.955 (15.22) 0.91 0.912 (17.67) 0.68

Accuracy 0.770 (10.86) 0.59 0.822 (16.04) 0.73

Format 0.855 (12.70) 0.73 0.993 (18.19) 0.53

Ease of use 0.629 (8.30) 0.40 0.719 (13.09) 0.68

Timeliness 0.712 (9.74) 0.51 0.883 (13.78) 0.76

a t values for factor structural coef®cients are indicated in parentheses.

116 R. McHaney et al. / Information & Management 36 (1999) 109±119

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cients indicate the validity of the latent constructs with

values ranging from 0.629 to 0.955. The t-values are

all signi®cant and the R2-values range from 0.40 to

0.91, indicating acceptable reliability for all factors.

4. Conclusions

Correlation analysis and con®rmatory factor ana-

lysis indicate that the EUCS instrument is psychome-

trically sound and valid in test and retest

administrations. Strong values for Cronbach's � indi-

cate good internal consistency in both the test and

retest administrations. Correlation analysis between

test and retest administrations of the instrument fails to

detect any problems with reliability; however, differ-

ence testing provides mixed results. While eleven of

the individual questionnaire item responses do not

show any signi®cant differences between administra-

tions, one does at the (p < 0.05) level. This difference

is re¯ected less signi®cantly at the subscale level

(p < 0.08) and is not re¯ected as a signi®cant differ-

ence in the global EUCS item (p � 0.15).

The mixed ®ndings with respect to the difference

testing does not necessarily indicate instability of the

underlying theoretical construct nor does it mean that

the instrument is ¯awed. These ®ndings might indicate

a memory or reactivity effect. A memory effect can

occur when respondents are able to recall the answers

given in a prior test administration. Since a month

passed between the initial test and the retest, the

likelihood of memory playing are role is diminished.

Reactivity is more likely to explain the differences

discovered between several of the items. Reactivity

occurs when the questionnaire respondents think

about the questions between the two administrations.

This effect is common among respondents who are not

used to answering detailed questions.

Another explanation for the mixed results may

relate to the very nature of the software systems being

evaluated. Several individual simulation systems rated

as highly successful in the initial response were rated

as unsuccessful in the follow-up response. An altered

rating might occur for several reasons: perhaps the

user's perception of the software system may have

changed or new problems may have come to the notice

of the user in the intervening month, alternatively, the

user may have become aware of additional informa-

tion about the operation of the system or of similar

systems that are better. It is also possible that the

system being modeled may have been put into opera-

tion during the intervening month and shows that the

simulation was not an accurate depiction, as originally

believed. This argument is strengthened by looking at

the questionnaire item with signi®cant differences:

A2ÐAre you satis®ed with the accuracy of the sys-

tem. Another possibility is that questions included on

the original questionnaire introduced a degree of

response bias. The initial survey asked detailed ques-

tions relating to numerous aspects of the system being

rated. These items were used to test a contingency

model for computer simulation success. The follow-up

survey summarized the initial responses and asked

only some of the EUCS questions. The initial EUCS

responses may have been in¯uenced by the thought

process used by the subject as they regarded each

characteristic of their system in great detail. As a

result, the respondent may have provided a shallower

assessment of the system re¯ected in a slightly lower

EUCS rating.

Although one item exhibited a signi®cant difference

between the test and retest applications of the EUCS

instrument, the overall ®ndings provide evidence in

support of its psychometric stability. In addition, other

tests suggest the instrument to be internally consistent.

Support for construct and convergent validity are also

present. In conclusion, this research indicates the

EUCS instrument can be used as a surrogate measure

of success for representational DSS, espceially for

discrete event computer simulation systems.

Appendix

EUCS instrument questions

C1: Does the system provide the precise informa-

tion you need?

C2: Does the information content meet your needs?

C3: Does the system provide reports that seem to be

just about exactly what you need?

C4: Does the system provide suf®cient informa-

tion?

A1: Is the system accurate?

A2:Areyousatis®edwith the accuracy of the system?

R. McHaney et al. / Information & Management 36 (1999) 109±119 117

Page 10: EUCS test–retest reliability in representational model decision support systems

F1: Do you think the output is presented in a useful

format?

F2: Is the information clear?

E1: Is the system user friendly?

E2: Is the system easy to use?

T1: Do you get the information you need in time?

T2: Does the system provide up-to-date information?

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Roger McHaney has current research interests in automated

guided vehicle system simulation, innovative uses for simulation

languages, and simulation success. Dr. McHaney holds a Ph.D.

from the University of Arkansas where he specialized in computer

information systems and quantitative analysis. He is currently an

Assistant Professor at Kansas State University. Dr. McHaney is

author of the textbook, Computer Simulation: A Practical

Perspective and has published simulation-related research in

journals such as Decision Sciences, Decision Support Systems,

International Journal of Production Research and Simulation &

Gaming.

Ross Hightower is an Assistant Professor of Management

Information Systems at the College of Business Administration,

University of Central Florida. His primary research interest is

computer-mediated communication, and information exchange in

groups. His work has appeared in journals such as Information

Systems Research, Decision Sciences, Information and Manage-

ment, and Computers in Human Behavior. He received his

doctorate in business administration from Georgia State University.

Doug White is an Assistant Professor at Western Michigan

University. He has published in Simulation and Gaming, IEEE:

Simulation Digest, Computers and Composition, and others. Dr.

White has worked for the Federal Reserve System and Oak Ridge

National Laboratories. Dr. White currently teaches computer

programming and acts as a networking consultant.

R. McHaney et al. / Information & Management 36 (1999) 109±119 119