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). For detailed instructions, please refer to Yang et al. (2026).