Several statistical methods are used to measure heterogeneity:
1. Cochran's Q Test: This test assesses whether the observed heterogeneity is greater than what would be expected by chance. A significant p-value indicates the presence of heterogeneity.
2. I² Statistic: This statistic quantifies the percentage of total variation across studies due to heterogeneity rather than chance. An I² value of 0% indicates no observed heterogeneity, while higher values indicate increasing heterogeneity.
3. Tau² (τ²): This is an estimate of the between-study variance in a random-effects meta-analysis. Larger values of τ² indicate greater heterogeneity.
