Statistical Analysis
All analyses were conducted using Comprehensive Meta-Analysis, Version 2.026. In order to standardize group differences on measures of olfactory performance, an effect size (Cohen’s d) was calculated by calculating the mean difference in scores for studies reporting contrasts of schizophrenia patients and healthy comparison participants and dividing this value by the pooled SD. Studies were weighted according to their inverse variance estimates in order to control for study differences in sample size when mean effect sizes were computed. Based on Cohen’s criteria,27 effect sizes are categorized as small (d = 0.2), medium (d = 0.5), or large (d ≥ 0.8). Confidence intervals (CI) and z-transformations of the effect size were used to determine whether mean effect sizes were statistically significant.