Eating Behaviors 13 (2012) 379–381

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Eating Behaviors

Confirmatory factor analysis for the Eating Disorder Examination Questionnaire:Evidence supporting a three-factor model

Jennifer Barnes ⁎, Tim Prescott, Steven MuncerTeesside University, Middlesbrough, UK

⁎ Corresponding author. Tel.: +44 7813 690 857 (moE-mail address: H8047526@live.tees.ac.uk (J. Barnes

1471-0153/$ – see front matter © 2012 Elsevier Ltd. Alldoi:10.1016/j.eatbeh.2012.05.001

a b s t r a c t

a r t i c l e i n f o

Article history:

Received 24 March 2012Accepted 16 May 2012Available online 23 May 2012

Keywords:Eating disorderEating Disorder Examination QuestionnairePsychometric propertiesConfirmatory factor analysis

Objective: The purpose of this investigation was to compare the goodness-of-fit of a one factor model with thefour factor model proposed by Fairburn (2008) and the three factor model proposed by Peterson and col-leagues (2007) for the Eating Disorder Examination Questionnaire (EDE-Q 6.0) (Fairburn and Beglin, 1994).Method: Using a cross-sectional design, the EDE-Q was completed by 569 adults recruited from universitiesand eating disorder charities in the UK. Confirmatory factor analysis (CFA) was carried out for both the stu-dent and non-student groups.Results: CFA indicated that Peterson et al.'s (2007) three factor model was the best fit for both groups withinthe current data sample. Acceptable levels of internal reliability were observed and there was clear evidencefor a hierarchical factor of eating disorder.

Discussion: The results of this study provide support for the three factor model of the EDE-Q suggested byPeterson and colleagues (2007) in that this model was appropriate for both the student and non-studentsample populations.

© 2012 Elsevier Ltd. All rights reserved.

1. Introduction

The Eating Disorder Examination Questionnaire (EDE-Q 6.0)(Fairburn and Beglin, 1994) is a self-report measure designed to as-sess eating disorder symptoms. The purpose of the study was to eval-uate the proposed three factor structure of the EDE-Q in comparisonwith other alternative structures. It is appropriate to use CFA ratherthan exploratory factor analysis when a researcher has some knowl-edge of the underlying latent variable structure. It is particularlyimportant in this case as Peterson et al. (2007) suggested that futureinvestigation used this technique.

CFA was used to verify the factor structure of the EDE-Q and to testout the hypothesis that a relationship exists between the observedvariables and their underlying latent constructs (Field, 2009). Thespecific purpose of this investigation was to use CFA in order to assessthe goodness-of-fit of a one factor model with the four factor modelproposed by Fairburn (2008) and the three factor model proposedby Peterson et al. (2007) in two groups of participants, student andnon-students, in order to assess the factor structure and internal reli-ability of the EDE-Q.

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rights reserved.

2. Method

2.1. Participants

Non-probability volunteer sampling was utilised in order to re-cruit participants. Participants were recruited from United Kingdom(UK) based eating disorders charities and from UK universities. Thesample consisted of a total of 569 adult participants, with 403 (71%)students and 166 (29%) non-students recruited from eating disordercharities. Approximately 91.8% of the student sample was female, aswas 95.8% of the sample recruited from eating disorder charities.

2.2. Measure

The Eating Disorder Examination Questionnaire (EDE-Q 6.0)(Fairburn and Beglin, 1994) is a self-report measure consisting of 28items. It yields a global score and four subscale scores: restraint,shape concern, weight concern, and eating concern. Items 13–18 elic-it behavioural frequency data rather than severity data; therefore,these items were not included in the analysis since the study exam-ined severity of symptoms rather than frequency.

2.3. Statistical analyses

The data were entered and analysed using SPSS version 18, Amos,and EQS 6. Confirmatory factor analysis was conducted using bothAmos andEQS. In thefirst instanceAMOSwas usedwithmaximum like-lihood estimation to investigate whether the models were appropriate

Table 1Confirmatory factor analysis of the EDE-Q.

Items Goodness of fit indices

Χ2/df df CFI RMSEA

One factor 22 6.38 418 .78 .097Four factor 22 4.62 404 .86 .08Three factor 21 4.67 372 .86 .08

380 J. Barnes et al. / Eating Behaviors 13 (2012) 379–381

for both groups of participants. In the second analysis EQS was used asthis can compute fit statistics that will be more accurate for Likertscale data. The internal reliability and factor structure of the EDE-Qwas examined. Lastly, we investigated the importance of a hierarchicalgeneral factor of eating disorder.

3. Theory

The EDE-Q has been shown to have good internal consistency in anumber of different samples (Becker et al., 2010; Luce and Crowther,1999; Mond, Hay, Rodgers, Owen, and Beumont, 2004; Peterson et al.,2007) and also good test retest reliability (Becker et al., 2010; Mondet al., 2004). However, there have been few studies which have exam-ined its factor structure. Peterson et al. (2007) found results thatsupported Fairburn's (2008) proposed eating concern and restraintsubscales, but found that weight and shape concern items mostlyloaded onto the same factor, which suggested that a three factormodel was a better fit to their sample. Becker et al. (2010) used prin-cipal axis factoring to request a four factor solution for the severityitems of the EDE-Q. In partial agreement with the Peterson et al.(2007) model, they found that the majority of the weight and shapeconcern items loaded onto their first factor. Becker et al. (2010) alsoreported medium to large intercorrelations between their factors,which supported the concept of a unitary global EDE-Q score.

A further study carried out by Hrabosky et al. (2008) also failed toreplicate the original subscales as proposed by Fairburn (2008) whenthey carried out an exploratory factor analysis on a sample of 167obese individuals. Their factor analysis elicited a four factor structurewhich partially replicated the Peterson et al. (2007) model since theyfound that the shape and weight concern items both loaded onto thesame factor and that there was a distinct restraint factor. Hraboskyet al. (2008) are the first researchers to carry out a confirmatory fac-tor analysis on the EDE-Q to the authors' knowledge. They reportedan acceptable fit using data based on their exploratory factor analysisfour factor model. However, this CFA only included 12 items from theEDE-Q. Furthermore, the factor structure elicited using individualssuffering from obesity and general population samples may differfrom the factor structure elicited using individuals suffering from an-orexia or bulimia. Further research is needed into the psychometricproperties of the EDE-Q, especially in terms of reporting the factorstructure for samples of individuals suffering from eating disorders.

4. Results

The non-student group recruited from eating disorder charitiesscored significantly higher overall on the EDE-Q (M=80.49, SD=31.42) than the student group (M=64.38, SD=31.42, t(567)=5.06, pb .005, d=0.47), as we expected. It is important to establishthe factor structure of the EDE-Q for samples both with and withouteating disorders, so we originally considered both groups together.Confirmatory factor analysis was conducted using Amos software(Arbuckle and Wothke, 1999). The first analyses compared a one fac-tor model with the four factor model proposed by Fairburn (2008)and the three factor model proposed by Peterson et al. (2007). Maxi-mum likelihood estimation was used and both groups were includedin the analysis; cases with missing values, however, were excluded.

The fit indices for these models are presented in Table 1. Lowerscores for the ratio of chi square to degrees of freedom (Χ2/df) andthe root mean square of approximation (RMSEA) indicate a better fitof the model (Browne and Cudek, 1993), whereas higher scores onthe comparative fit index (CFI) indicate a better fit (Bentler, 1990).Clearly the one factor model had the worst fit and there was very littleto choose between the three and four factor models. The four factormodel, however, was inadmissible because of the presence ofHeywood cases, which are parameter estimates outside of the normalrange. In this case several standardised regression weights were

higher than 1. It is also worth noting that the three factor model wasalso more parsimonious and, therefore, would normally be preferred.

It is possible that the model fits one group of participants signifi-cantly better than another, which would mean that the model didnot have an invariant factorial structure. We tested this by holdingthe factor loadings constant and equal for both groups and showedthat the fit statistics were not significantly different (Χ2=29.4,df=18, p>.05). Thus the three factor model was appropriate bothfor the student and non-student groups, although non-studentsscored significantly higher on EDE-Q total.

While it seems clear that the Peterson et al. (2007) three factormodel is the best, the fit statistics from maximum likelihood estima-tion were disappointing. It is important to recognise, however, thatmaximum likelihood estimation often underestimates model fitwhen the model contains categorical variables (Bentler, 2005). TheEDE-Q is based on an ordered categorical scoring system and so thecurrent fit statistics will be an underestimate.

One approach to this problem would be to use asymptotic distri-bution free methods of estimation, which are possible with AMOS.The difficulty in this case, however, is that asymptotic distributionfree methods require huge sample sizes (Browne, 1984). Another ap-proach is to correct the fit statistics while still using a method of esti-mation which works with smaller samples (Bentler, 2005). In order toprovide the appropriate fit statistics we re-analysed the data usingEQS 6 (Bentler and Wu, 2002), which is able to take the categoricalnature of variables into account. The robust fit statistics, which are ap-propriate for categorical data (Bentler, 2005), were considerably bet-ter with the CFI=.96 and the Bentler–Bonett normed fit index=.95,with numbers over .95 representing good fit (Hu and Bentler, 1999).Furthermore, the Cronbach's alpha measure of reliability was .96 forthe whole scale, .94 for the shape/weight factor (F1), .89 for the eat-ing concern factor (F2) and .83 for the restraint factor (F3).

It should also be noted that the three factors were strongly corre-lated with each other with a correlation of r=.80 between Factor 2and Factor 3, r=.84 between Factor 1 and Factor 2 and r=.76 be-tween Factor 1 and Factor 3. This means that there was clearly evi-dence for a hierarchical factor of eating disorder which had loadingsof .9 on shape/weight, .94 on eating concern and .85 on restraint.The hierarchical general factor explained an average of 50.3% of thevariance in individual items, using the Schmid–Leiman transformation(Schmid and Leiman, 1957).

5. Discussion and conclusion

In agreement with previous studies (Becker et al., 2010; Luce andCrowther, 1999; Mond et al., 2004; Peterson et al., 2007), this investi-gation found good levels of internal reliability for the EDE-Q. ThePeterson et al. (2007) three factor model is strongly supported bythe data from both participant groups in this study. The combinationof the weight and shape concern items into one factor as suggestedby Peterson et al. (2007), with the other two factors closely resem-bling the eating concern and restraint subscales, was the best fit tothe current sample of male and female adults from UK based eatingdisorder charities and Universities. In addition, the separation of theshape and weight concern self-evaluation items, as suggested by pre-vious studies (Becker et al., 2010; Hrabosky et al., 2008; Peterson et al.,2007), was supported by the current sample. Furthermore, the total

381J. Barnes et al. / Eating Behaviors 13 (2012) 379–381

score on the items in the Peterson et al. (2007)model will be a reliablemeasure of eating disorders. These findings suggest that the currentscoring system for the EDE-Q may be improved by the use of a threefactor model rather than the original four factor model as suggestedby Fairburn (2008). The current scoring system for the EDE-Q maybe improved by combining the weight and shape concern items intoone factor giving a three factor rather than a four factor structure.

A strength of the current study is the large sample size recruitedwhich allowed the researchers to conduct a confirmatory factor analy-sis. Furthermore, the recruitment from both a student population witha low level of eating disorder symptoms and from eating disordercharitymemberswith a high level of eating disorder symptoms allowedthe comparison of the EDE-Q's factor structure across these differentpopulations. However, the current sample was mostly female withrelatively few male participants, limiting the generalisability of thefindings. Further investigation of the psychometric properties of theEDE-Q in different population samples would be beneficial in order tofurther validate the Peterson et al. (2007) model.

Despite the limitations of the current study, it is hoped that thefindings will be useful in determining the psychometric propertiesof the EDE-Q in terms of its factor structure in clinical and communitysamples.

Role of funding sourcesA £200 bursary was provided by the University of Teesside in order to finance the

current research. This study was conducted as part of the award of Doctorate in ClinicalPsychology. The study gained ethical approval from the School of Health and SocialCare Research Governance and Ethics Committee.

ContributorsAuthor Dr. Jennifer Barnes designed the study, wrote the protocol, conducted liter-

ature searches and recruited participants under the supervision of Dr Tim Prescott.Dr Steven Muncer conducted the statistical analysis. All authors have contributed toand have approved the final manuscript.

Conflict of interestAll authors declare that they have no conflicts of interest.

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