Fig. 3
Placebo response in scales measuring repetitive behaviors. Squares and bars represent standardized mean changes (SMC) and 95% confidence intervals for each study. The size of the square is proportional to the weight of the study in the meta-analysis. The diamond represent the pooled SMC. Heterogeneity is quantified with a χ2 test (Q) and I2. *In Chugani 2016, standard errors might have been reported as SDs. Therefore, we calculated SDs from the reported values (no reply from the corresponding author). In Amminger 2007, ABC-S was rated by clinicians of the day care center. Scale: the scale used (clinician rated scales based on observation or interviews were preferred in the primary analysis); n: the number of participants on placebo; mean: mean change from baseline to endpoint (negative values for improvement); sd: the standard deviation used for the standardization (baseline standard deviations were preferred); SMC: standardized mean changes, 95% CI: 95% confidence intervals, k = total number of studies included in the analysis