METHODS: The data were taken from the online assessment results of two groups, with a total of 765 participants. The instruments studied were Self-Rating Questionnaire (SRQ-20), post-traumatic stress disorder (PTSD), and Center for Epidemiological Studies Depression Scale-10 (CESD-10), used in the online assessment. Data analysis used Rasch modeling and Winsteps applications. Validity and reliability were tested, and data were fit with the model, rating scale, and item fit analysis.
RESULTS: All the scales for outfit mean square (MnSq) were very close to the ideal value of 1.0, and the Chi-square test was significant. Item reliability was greater than 0.67, item separation was greater than 3, and Cronbach's alpha was greater than 0.60; all the instruments were considered very good. The raw variance explained by measures for the SRQ-20, PTSD, and CESD-10 was 30.7%, 41.6%, and 47.6%, respectively. The unexplained eigenvalue variances in the first contrast were 2.3, 1.6, and 2.0 for the SRQ-20, PTSD, and CESD-10, respectively. All items had positive point-measure correlations.
CONCLUSION: The internal consistency of all the instruments was reliable. Data were fit to the model as the items were productive for measurement and had a reasonable prediction. All the scales are functionally one-dimensional.