Statistical Analysis
Data were analysed according to an Intention-to-Treat analy-sis, i.e., the data from subjects who refused to start with the treatment or that dropped out during the intervention period were also taken into consideration. Accordingly, the data from those participants were treated following a “last observation carried forward” (LOCF) protocol with the pre-measures also taken for the post-measure. This procedure is rather conserva- tive and implies that no improvement has taken place due to the intervention.
Statistical analysis was based on an analysis of variance (ANOVA) with the between-group factor Treatment (PP vs. CG) and the repeated measures factor Time (pre vs. post) for each of the dependent variables (depression, satisfaction with life, positive and negative affect, optimism, resilience). Prior to each ANOVA, a test for homogeneity of variances was applied. A p-value ≤ .05 was regarded as significant.