This online calculator computes the new measure of heterogeneity, $I_A^2$, for quantifying the heterogeneity at the study population level (Yang et al., 2025). It ranges from 0 to 1, with higher values indicating greater heterogeneity between the studies. Moreover, $I_A^2$ is not influenced by the study sample sizes, making it an absolute measure of heterogeneity between the studies.

In contrast, the well-known $I^2$ statistic (Higgins and Thompson, 2002; Higgins et al., 2003) measures the heterogeneity between the observed effect sizes and is therefore highly dependent on the study sample sizes. A major limitation of $I^2$ is that it increases rapidly toward 1 when the sample sizes become large, making it a relative measure of heterogeneity between the studies.

To facilitate implementation, we offer two Data Input options as follows, depending on whether the Q or $I^2$ statistic is already available. This online calculator accommodates both single-arm and two-arm studies and supports commonly used effect sizes for continuous outcomes, including the mean difference (MD) and the standardized mean difference (SMD).