Psychometric properties of the Muscle Appearance Satisfaction Scale among Irish and British men § Travis A. Ryan a, *, Todd G. Morrison b a School of Psychology, National University of Ireland, Galway, University Road, Galway, Ireland b Department of Psychology, University of Saskatchewan, Saskatoon, SK, Canada S7N 5A5 Introduction The Muscle Appearance Satisfaction Scale (MASS; Mayville, Williamson, White, Netemeyer, & Drab, 2002) is a commonly employed 19-item measure of muscle dysmorphia (MD) sympto- matology. Based on principal components analysis (PCA) on data obtained from weight-lifting students in the United States, Mayville et al. identified a 5-component solution: Bodybuilding Dependence (5 items), Muscle Checking (4 items), Substance Use (4 items), Injury (3 items), and Muscle Satisfaction (3 items). These components evidenced satisfactory 2-week test re-test reliability (rs ranged from .76 to .89), alpha coefficients (as ranged from .73 to .80), and construct validity (e.g., scores on the MASS correlated positively with scores on a measure of body dysmorphic disorder). Although the findings furnished by Mayville et al. (2002) are promising, it should be noted that, in testing the structure of the MASS, several of the statistical choices were problematic. First, the authors used PCA for structure detection, whereas exploratory factor analysis (EFA) is recommended (Worthington & Whittaker, 2006). Second, the authors used varimax rotation, which does not permit factors (or components) to correlate. As Mayville et al. were testing dimensions of MD, which they found to be positively intercorrelated (mean r = .32), oblique rotation, which allows for correlation(s) between factors, would have been preferable (Fabrigar, Wegener, MacCallum, & Strahan, 1999). Third, to determine the number of factors to retain, the authors employed the eigenvalue greater than one guideline in conjunction with inspection of the scree plot. The former is not recommended due to its arbitrariness and propensity to result in factor over- or underextraction (Fabrigar et al., 1999). Fourth, the authors stated that only items loading on one component at .40 or greater were retained. However, no specific criteria regarding cross loadings were given and inspection of the scale’s component loadings reveals that several items loaded on other components at >.30. Worthington and Whittaker (2006) contended that such items reflect the influence of multiple factors and should be deleted. Mayville et al. (2002) then conducted a confirmatory factor analysis of the MASS using a sample of self-identified weight lifters from the United States. No information was provided regarding the multivariate normality of the data and indices of fit were less than optimal (e.g., Goodness of Fit Index [GFI] = .89). Given the ambiguous nature of the scale’s structure, the primary purpose of this study was to test its dimensionality in accordance with most recommended criteria for exploratory and confirmatory factor analyses. A subsidiary purpose was to examine the psychometric properties of the MASS using non-bodybuilder and weight-lifting populations from outside the United States. To date, most research on MD has been conducted with American men (e.g., Cafri, Body Image 7 (2010) 246–250 ARTICLE INFO Article history: Received 24 August 2009 Received in revised form 26 February 2010 Accepted 26 February 2010 Keywords: Muscle dysmorphia Psychometrics Exploratory factor analysis Confirmatory factor analysis Male body image Social desirability bias ABSTRACT The psychometric soundness of the Muscle Appearance Satisfaction Scale (MASS; Mayville, Williamson, White, Netemeyer, & Drab, 2002), a measure of muscle dysmorphia symptoms, was investigated using two independent online samples of Irish and British men (ns = 307 and 306, respectively). Exploratory and confirmatory factor analyses showed that, compared to the original 5-component solution for the 19-item MASS, a 6-item unidimensional version offered better fit to the data. Findings further upheld the internal consistency reliability, construct validity (e.g., via its associations with internalization of the muscular ideal and physical appearance comparisons), and discriminant validity (e.g., via its nonsignificant relationship with social desirability) of the MASS’s scores. The limitations associated with the current research are discussed and directions for future research are articulated. ß 2010 Elsevier Ltd. All rights reserved. § Travis A. Ryan’s work on this manuscript was made possible by the Lady Gregory Doctoral Research Fellowship Scheme of the College of Arts, Social Sciences, & Celtic Studies, National University of Ireland, Galway. This funding source had no involvement in the research. * Corresponding author. Tel.: +353 91 495118; fax: +353 91 521355. E-mail addresses: travisryan13@gmail.com (T.A. Ryan), todd.morrison@usask.ca (T.G. Morrison). Contents lists available at ScienceDirect Body Image journal homepage: www.elsevier.com/locate/bodyimage 1740-1445/$ – see front matter ß 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.bodyim.2010.02.008