THE FACTOR STRUCTURE OF THE ANOREXIA-NERVOSA INVENTORY FOR SELF-RATING IN A POPULATION-BASED SAMPLE AND DERIVATION OF A SHORTENED FORM

The Anorexia Nervosa Inventory for Self-Rating (ANIS) was the first in strument covering aspects of the general psychopathology of eating dis orders alongside eating attitudes, but its factorial integrity in non- clinical samples has not yet been investigated. Thus, this report is a imed at assessing the factorial structure of the ANIS with different m ethods of extraction and rotation. Data from a population-based random sample of German-speaking Italian schoolgirls aged 11-20 years (n = 1 402) were used. The instruments included the ANIS and the Eating Behav iour Severity Scale. The internal consistency (Cronbach's alpha of the ANIS and four of its subscales was 0.70-0.88; however, reliability of the subscales ''Sexual Anxieties'' and ''Obsessive-Compulsive Traits' ' was doubtful in non-clinical female adolescents. The original six fa ctors were convincingly replicated by maximum likelihood extraction an d principal component analysis. As some items and subscales showed wea knesses, a shortened 20-item version was derived containing the subsca les ''Figure Consciousness'', ''Feelings of Inadequacy'', ''Adverse Ef fects of Meals'', and ''Bulimia''. All items showed factor loadings > 0.50 and item-total-correlations between 0.30 and 0.80. Internal consi stency of the ANIS-20 total scale (0.90) was remarkable as it was for the subscales (0.70-0.85); discriminant validity as assessed by a cros s-validational approach (random split-half samples) was not affected b y this abbreviation. In conclusion, both the original ANIS and the ANI S-20 are psychometrically sound instruments. Because brevity is import ant in screening studies, the short form is recommended.