Obesity Epidemiology

Table 7.3 Variance Components for Total, Occupational, and Nonoccupational Physical Activity in Men and Women, Seasonal Variation of BloodCholesterol Study, Worcester, Massachusetts, 1994-1998Type of Activity*Total Occupational NonoccupationalVariance 95% CI † TotalPercentage ‡ Variance 95% CITotalPercentage Variance 95% CITotalPercentageMen (n = 300)Subject 39.3 32.2-49.0 31 37.9 31.2-46.9 35 8.7 6.6-12.0 14Season 7.1 4.8-11.5 6 3.0 1.8-6.2 3 6.1 4.4-8.9 10Day 19.3 15.8-24.1 15 28.3 24.8-32.5 26 8.9 6.9-11.8 14Residual 60.7 56.7-65.1 48 38.3 35.7-41.2 36 39.9 37.3-42.7 63Total 126.4 107.5 63.5Women (n = 280)Subject 10.4 8.2-13.6 19 9.6 7.8-12.1 29 5.5 4.1-7.7 13Season 3.6 2.5-6.0 7 1.0 0.5-2.5 3 3.3 2.4-5.1 8Day 6.5 5.0-8.9 12 6.7 5.6-8.2 20 7.4 6.0-9.3 18Residual 32.9 30.7-35.3 62 15.7 14.5-16.9 48 24.9 23.2-36.7 61Total 53.5 32.9 41.1*Units for physical activity variables were metabolic equivalent-hours/day.†CI, confidence interval.‡Percentage of total variance attributable to a given source.Reproduced with permission from Matthews CE, Hebert JR, Freedson PS, et al. Sources of variance in daily physical activity levels in the seasonal variation of blood cholesterol study. Am J Epidemiol.2001;153:987-995. 103