Table 3.
Results of the simple meta-regressions of continuous moderator variables on the retention success rate estimates.
| Moderator variable | k | bj | F | p | QE | R2 |
|---|---|---|---|---|---|---|
| Mean age (years) | 23 | 0.229 | 0.553 | 0.465 | 204.315*** | 0.03 |
| SD of age (years) | 11 | 1.193 | 1.848 | 0.207 | 46.612*** | 0.27 |
| Sample size | 27 | −0.009 | 13.776 | 0.001 | 151.956*** | 0.37 |
| Gender (% male) | 16 | −0.091 | 2.984 | 0.152 | 156.351*** | 0.29 |
| Year of the study | 27 | −0.035 | 0.499 | 0.486 | 235.331*** | 0.03 |
k = number of studies. bj = regression coefficient of each predictor. F = Knapp-Hartung’s statistic for testing the significance of the predictor (the degrees of freedom for this statistic are 1 for the numerator and k – 2 for the denominator). p = probability level for the F statistic. QE = statistic for testing the model misspecification. R2 = proportion of variance accounted for by the predictor. ***p < 0.0001.