with wider confidence interval), but the results from the two models usually agree where there is no heterogeneity. The random effects model will tend to give a more conservative estimate (i.e. Under the random effects model (DerSimonian and Laird) the true effects in the studies are assumed to vary between studies and the summary effect is the weighted average of the effects reported in the different studies (Borenstein et al., 2009). Under the fixed effects model, it is assumed that the studies share a common true effect, and the summary effect is an estimate of the common effect size. The pooled value for the estimate, with 95% CI, is given both for the Fixed effects model and the Random effects model. The program lists the results of the individual studies included in the meta-analysis: the estimate and 95% confidence interval.