This sample size provided 80% power for hierarchical multiple regression to detect small to medium effects at the 0.05 significance level with a 20% response rate.
Although there were small effects at post-test and medium effect sizes at follow-up among the intervention conditions, there were no consistent overall effects for conditions.
A sample size of 158 women is sufficient to detect an association between patient characteristics and consultants' behaviours of a magnitude of 0.3, that is a small to medium effect size, at a 0.05 level of significance with a power of 80%.
Power calculation revealed that 36 participants per study arm will result in 80% power to detect medium effect size (0.3) at a significance level of 0.05 (two sided).
Detectable linear regression effect sizes were targeted between small to medium effects for unadjusted (by convention small to medium effect size set at 0.02 < f < 0.15) to medium to large (by convention medium to large effect size set at 0.15 < f < 0.35) for adjusted (one predictor, six covariates) regression models.
To be on the safe side, we estimated a medium effect of F.15 at three months follow-up, and further increased the sample to account for clustering of the data, which lead to 65 participants per condition.
Small to medium effect sizes were obtained at post-training and follow-up, respectively.
On the other hand, in brain morphological analyses, our sample size had sufficient power (>80%) to detect a genotype effect on GM volumes at medium effect size (Cohen's d) of 0.25 or greater.
Power analysis indicates that an overall sample size of 121 is required to detect a medium effect size (approx.70) at the.05 alpha level using linear techniques (power = .80).80
From the three cohorts providing both SSD and AP outcome data, the birth cohort provided consistent evidence (medium and large effects) of low IQ as an antecedent of SSD [ 29, 135], and mixed evidence of low IQ as an antecedent of AP (a medium effect noted for mania assessed at age 26 years [ 29], but no effect at age 32 years [ 135]).
