Table 3.
Effect Size by Study
| Study | Na | Meanb Effect Size (r) |
| Wirt and Simon 195919 | 39 | 0.08 |
| Schooler et al. 196721 | (254) | (Negative) |
| May et al. 1976a, 1976b, 1981;20,30,31 Wyatt, Green, and Tuma 199726 | 22–225 | 0.14 |
| Rappaport et al. 197818 | 80 | −0.18 |
| Bola and Mosher 200325 | 106–129 | −0.19 |
| Ciompi et al. 1992, 199323,34 | 44 | −0.09 |
| Lehtinen et al. 200024 | 106 | −0.16 |
| Median Effect Size | 395–623 | −0.13 |
| Weighted Mean Effect Sizec,d | 395–623 | −0.09e (.09) |
Note: Range of study effect sizes: −.19 to .14.
a
Number of subjects included in effect size estimates.
b
A negative effect size indicated the initially nonmedicated group had better outcomes. Means calculated using Fisher's Z transformation.
c
Effect sizes weighted by the inverse variance for each study.
d
Chi-square test indicates nonheterogeneity of effect sizes (χ2 = 2.32, df = 5, not significant).
e
Z = −1.00, not significant; fixed effects 95% CI: (−.27, .09).