Introduction: The aim of this study was to examine confirmatory factor structure, reliability and validity of the Achenbach Youth Self-Report Scale (YSR) for a group of 11 to 18 years old monozygotic (MZ) and dizygotic (DZ) youth twins.
Method: n=236 pair of twins (133 MZ, 103 DZ, 259 girls, and 213 boys) were selected through announcement of the Iranian Association of Twins and completed the YSR scales. To investigate confirmatory factor structure of the data WLS estimation method was applied using Item parceling procedure. For evaluating adequacy and Goodness of fitness of the model NNFI, RMR, RMSEA, CFI, AGFI, GFI, ECVI, X2, X2/doff, ïï£2 indices were computed . Optimal levels of test-retest reliability, internal consistency and inter-rater reliability scores were estimated for the YSR scale.
Results: Findings supported the goodness of fitness of eight-factor oblique factor structure of the YSR. Construct-related validity of the scale was calculated according to correlation coefficients between the scores on the YSR and three subscales scores of the Junior Essence Personality Questionnaire (JEPQ).
Conclusions: Results supported the confirmatory factor structure, reliability and validity of the YSR for research and clinical diagnostic applications.