Results
Overall Meta-Analysis Results in Schizophrenia
Across all studies with a schizophrenia or schizophrenia-plus cohort, the overall effect size for olfactory processing tasks (k = 161; 4 491 schizophrenia patients and 4 408 controls) was −0.74 [95% CI = −0.83 < δ < −0.65], which is moderate to large in strength (see figure 1). An analysis of homogeneity including all studies revealed significant variance among study effect sizes that would support examining the effects of moderator variables (QB[160] = 630.0, P < .001). In order to understand the variability among effect sizes, we examined psychometric, clinical, and demographic variables that might explain this heterogeneity.