Construct Validity
The AAMQ-13 had 13 items; hence, it was posed that at least 130 patients
were needed to complete the questionnaire (32). The AAMQ-13 was
completed by 220 patients (7 cases were excluded as they were clear
outliers).
The Principal Component Analysis revealed the presence of two components
having an eigenvalue more than one (5.081 and 1.648). The two components
explained a total of 51.76% of the variance, with component one
contributing 39.08% and component two contributing 12.68% of the
variance.
Varimax rotation showed that both components had a number of good
loading and most of the variables were loaded substantially on one
component. Items demonstraing a loading of 0.3 or greater were
considered to measure a factor, and items (n= 3) which loaded 0.4 or
more onto both factors were grouped according to the highest loading.