Validity and reliability of optimism questionnaire among adolescents based on theory of planned behavior

This study aimed to normalize and examine the validity and reliability of the optimism questionnaire based on the theory of planned behavior among the first-grade high school male adolescents. the study was conducted on 170 male students in the first grade of high school. the data were gathered using a researcher–made questionnaire containing 49 questions. in order to determine the validity of the questionnaire structure, exploratory factor analysis (efa) and confirmatory factor analysis (cfa) were performed using the spss-19 and sas (version 19) software. high internal consistency values were obtained for all the subscales. the results of factor analysis showed that 14 significant factors had eigenvalues greater than 1.0 and 71.22% of the variance were explained by these factors. in cfa method, four factors were considered for the 45 questions of the questionnaire based on the theory of planned behavior, which explained 39.98% of the variance. the results indicated that the optimism questionnaire was a valid and reliable instrument to be used among the students in the first grade of high school.