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. 2011 Apr;101(4):751–758. doi: 10.2105/AJPH.2010.194381

TABLE 4.

Linear and Cubic Mixed-Effects Moderator Analyses of Treatment Versus Control Postintervention Comparisons: Meta-Analysis of Interventions to Increase Physical Activity (n = 74 852)

Linear Qmodel Inline graphic
Moderator k M SD b I2 L C L C
Publication year (minus 1960) 206 39.41 6.26 −0.008 0.63 9.9*** 10.8** 0.17 0.17
Participant characteristics
    Mean sample age, y 136 47.31 10.55 0.002 0.48 1.2 3.0 0.15 0.15
    Female, % 163 0.60 0.25 0.027 0.57 0.2 1.4 0.16 0.16
    Racial/ethnic minority, % 52 0.25 0.31 0.030 0.58 0.1 1.2 0.18 0.18
    Education, y, mean 13 12.89 1.49 0.117 0.54 2.5 3.3 0.25 0.30
    Attrition, control, % 130 0.17 0.15 0.138 0.47 1.0 2.9 0.14 0.14
    Attrition, treatment, % 131 0.18 0.14 −0.131 0.46 0.9 1.2 0.13 0.14
    Attrition, all, % 126 0.17 0.14 0.041 0.47 0.1 1.6 0.14 0.14
    Difference in % attrition 126 0.00 0.09 −0.583 0.46 6.6*** 8.9** 0.14 0.14
    Log odds ratio of attrition 96 0.01 0.72 −0.071 0.49 4.5** 6.2 0.14 0.14
 Log10 days since intervention 104 2.09 0.61 −0.016 0.44 0.1 4.6 0.14 0.14
Intervention characteristics
    No. behavioral strategies 206 1.04 1.34 0.012 0.62 0.8 3.1 0.17 0.17
    No. cognitive strategies 206 0.70 0.93 −0.004 0.63 0.0 4.6 0.17 0.17
    No. strategies 206 3.17 3.07 0.005 0.63 0.8 1.9 0.17 0.17
 Log10 recommend min/wk 46 2.18 0.13 −0.183 0.60 0.4 1.3 0.19 0.20
 Log10 recommend supervised physical activity 27 3.25 0.51 0.133 0.54 0.7 2.0 0.28 0.28
 Log10 recommend motivate/educate 50 1.97 0.72 −0.002 0.57 0.0 4.3 0.18 0.19
 Log10 recommend total minutes 59 2.01 0.76 0.043 0.55 0.8 4.7 0.19 0.19

Note. C = cubic; I2 = quantification of degree of heterogeneity; k = number of (possibly dependent) effect size estimates; L = linear, M = weighted mean; Qmodel = attributable to all polynomial terms of moderator (x) in linear (b1x) or cubic (b1x + b2x2 + b3x3) model, distributed as χ2 on df = m under H0: b = 0, where b is b1,or [b1 b2 b3]T, respectively, for linear or cubic model. Polynomial models with degree m = 1 or 3: Each moderator's weighted mean and SD were computed from all available cases. Publication year variable modified by subtracting 1960 from the actual year of publication. Moderator centered at the weighted mean. Analysis reported if k ≥ m + 5.

**P < .05; ***P < .01, for Qmodel.