Calculate I² (Inconsistency) in Meta-Analysis
I² (inconsistency) is a crucial metric in meta-analysis, quantifying the amount of heterogeneity among study results. Accurately calculating I² is vital for drawing reliable conclusions from your research.
- Enter the number of studies.
- Input the effect sizes of each study, separated by commas.
- Input the variances of each study, separated by commas.
- Click ‘Calculate’.
The formula for calculating I² is complex and involves inverse variance weighting, sum of squares, and degrees of freedom. For detailed calculations, see this authoritative source.
| Method | I² Value |
|---|---|
| Fixed-Effects | 0.25 |
| Random-Effects | 0.32 |
- Always check for publication bias before interpreting I².
- Consider using the I² statistic alongside the Q statistic for a more comprehensive analysis.
What does a high I² value indicate?
High I² values (>75%) suggest substantial heterogeneity among studies, indicating that the studies may have different effects.
How can I interpret I² values?
I² values can be interpreted using the following scale: 0-25% (low), 25-50% (moderate), 50-75% (substantial), and >75% (considerable).
For more information, see CDC’s guide on meta-analysis and UNC’s detailed explanation of I².