Submitted to: Medicine and Science in Sports and Exercise
Publication Type: Abstract Only
Publication Acceptance Date: 3/19/2007
Publication Date: 5/7/2007
Citation: Miller, F., Dishman, R.K., Bray, M.S., McFarlin, B., Jackson, A.S. 2007. Reliability and norms for the 10-item self-motivation inventory: The TIGER Study [abstract]. Medicine and Science in Sports and Exercise. 39(5 Suppl):S340. Interpretive Summary:
Technical Abstract: The Self-Motivation Inventory (SMI) has been shown to be a predictor of exercise dropout. The original SMI of 40 items has been shortened to 10 items and the psychometric qualities of the 10-item SMI are not known. To estimate the reliability of a 10-item SMI and develop norms for an ethnically diverse population. The 10-Item scale was administered to a sample of 778 participants (35.2% male and 64.8% female), who ranged in age from 17 to 30 y. The ethnic make-up of the sample was: 32% Caucasian; 26.3% African American; 24.7% Hispanic; 7.2% Asian; 4.4% Asian Indian; and 5.4% other. Cronbach’s alpha reliability estimate of the 10-item SMI was 0.83 with a standard error of measurement of 2.3. The inter-item correlations among all 10 items were statistically significant (p < 0.05). The SMI was significantly correlated with percent body fat (r = -0.165, p <.001) and estimated VO2max (r = .204, p<.001). ANOVA showed there was no significant gender effect (p = 0.095), but there was a significant ethnic group effect (p = 0.01). Bonferroni post hoc tests revealed the SMI for Asians was 2.9 units lower than African Americans (p = .01). The mean (+/- SD) and sample size for the total sample and ethnic groups were: total 40.6 +/- 5.6, n= 695; Caucasians, 40.4 +/- 5.6, n= 239; African American, 41.4 +/- 5.4, n= 194; Hispanic, 40.8 +/- 5.6, n=177; Asian, 38.5 +/- 5.6, n= 53; and Asian Indian, 39.4 +/- 6.5, n=32. The reliability of the 10-Item SMI for this population is 0.83 (SEM = 2.3). Males and females did not differ in SMI. The only ethnic difference was African Americans had a higher SMI mean than Asians. The descriptive statistics were used to develop percentile rank norms for adults, age 17 to 30 y.