Furthermore, when participants were classified according to an external criterion (i.e., the Q-EDD), results from the between-group comparisons showed that differences across the ED groups on the EAT-40 scores were not statistically significant, while participants with ED did significantly differ from the symptomatic and the asymptomatic groups.
While ED diagnosis was established according to results from the Q-EDD in the Study 2 by Rivas et al.
Propiedades psicometricas del Cuestionario para el Diagnostico de los Trastornos de la Conducta Alimentaria (Q-EDD) [Psychometric properties of the Questionnaire for Eating Disorder Diagnoses (Q-EDD)].
Descriptive statistics of the EAT-40 scores for the Q-EDD groups Q-EDD Groups N Mean SD Minimum Maximum AN 22 68.68 22.07 34 105 BN 35 63.31 20.60 17 106 EDNOS 26 58.69 25.78 19 103 Symptomatic 26 34.50 31.12 3 108 Asymptomatic 75 9.51 8.11 1 51 Total 184 37.30 31.86 1 108 Q-EDD: Questionnaire for Eating Disorder Diagnoses; AN: Anorexia Nervosa; BN: Bulimia Nervosa; EDNOS: Eating Disorders Not Otherwise Specified.
Some psychometric properties of the Spanish version of the Q-EDD have been explored in two previous studies among high school students and outpatients with ED (Rivas et al., 2001).
When the Q-EDD subgroups were separately considered, KMO indices were .743, .895, and .909 for the ED, Symptomatic, and Asymptomatic groups, respectively.
'Prevalence' in this study is taken as the base rate or the subject proportion of the sample showing a state of ED (Symptomatic, ED) classified by Q-EDD.
The cutoff point is 19 and the A UC is .70 which shows a moderate accuracy of EAT-26 measure in identifying clinically important degrees of ED (Asymptomatic and Symptomatic) in subjects classified by Q-EDD (see Figure 1).
The cut-off is 44 and the AUC is .73 showing a moderate accuracy of EAT-26 measure in identifying clinically important degrees of ED (Symptomatic and ED) in subjects classified by Q-EDD (see Figure 2).
Study 2 included the same questionnaires used in Study 1: the EAT-26 and the Q-EDD.
Table 2 shows the results of the classification, comparing the Q-EDD diagnoses (observed outcome category, Y) with those estimated as a function of the EAT-26 scores (predicted outcome category, [??]).
.127 .014 9.282 sub.3] (a) Reference category : Asymptomatic ([[alpha].sub.1], = 0 and [[beta].sub.1] = 0) Table 2 Classification table Predicted category Observed 0 [less than 21 [less than 57 [less than Total category or equal to] or equal to] or equal to] (Q-EDD x [less than x [less than x [less than diagnosis) or equal to] or equal to] or equal to] 20 56 78 Asymptomatic Symptomatic Eating disorder Asymptomatic 503 22 0 525 Symptomatic 171 43 3 217 Eating Disorder 18 18 0 36 Total 692 83 3 778