Reliability, validity and internal consistency of social support and self-efficacy scales for physical activity in adolescents with 10 to 14 years of age

OBJECTIVE To analyze the reliability, validity and internal consistency of the physical activity social support (SSS) and self-efficacy (SES) scales among adolescents aged 10-14 years. METHODS The reliability study included 171 adolescents (mean age=12.3±1.0 years, 59.6% female) and validity and consistency study with 1,107 (mean age=12.0±1.0 years, 52.7% female). The SSS had 15 items and the SES eight items. Reliability was determined by Spearman's correlation analysis (rho) and validity and internal consistency by factor analysis (exploratory - EFA and confirmatory - CFA) and the composite reliability (CR), respectively. RESULTS The reliability of SSS (father: rho=0.80; p<0.001 | mother: rho=0.76; p<0.001 | friends: rho=0.75; p<0.001) and SES (rho=0.72; p<0.001) were considered high. In the EFA, three factors were identified for the SSS (father, mother and friends - five items each) and one factor for SES (five items), confirmed in the CFA. Quality parameters of adjustment in the final models were satisfactory for SSS (chi-square=240.5 [p<0.001]; root mean square residual - RMR=0.05; root mean square error of approximation - RMSEA=0.04 [90%CI 0.04-0.05]; goodness of fit index - GFI=0.97; adjusted goodness of fit index - AGFI=0.96 and comparative fit index - CFI=0.97) and SES (chi-square=5.4 [p=0.07]; RMR=0.01; RMSEA=0.04 [90%CI 0.00-0.08]; GFI=0.99; AGFI=0.99 and CFI=0.97). Internal consistency was considered satisfactory for SSS (CR: father=0.79, mother=0.77, friends=0.78) and low for SES (CR=0.38). CONCLUSIONS The scales showed satisfactory levels of reliability and of construct validity. However, only the SSS showed adequate levels of internal consistency.