To determine whether the intervention led to a
clinically meaningful and reliable change the reliable change index was computed, as recommended by Jacobson and Truax.39 Because population norms for the GHQ - 12 and PSOC were not available for the present study population, we calculated the SE of difference (Sdiff) based on the pretest scores for the intervention and control group combined, assuming a
measurement reliability of 0.8 for each measure.