The `effectsize` package, developed by Mattan S. Ben-Shachar, Daniel Lüdecke, and Dominique Makowski, is designed to estimate various standardized effect size indices and their confidence intervals from a wide range of statistical models. This package addresses the need for assessing the strength of observed associations, facilitating comparisons between predictors, and providing standardized measures that are not tied to the units of measurement. Key features include: - **Standardized Differences**: Functions for estimating Cohen’s d, Hedge’s g, and Glass’ Δ for paired and independent samples. - **Contingency Tables**: Estimation of Pearson’s φ and Cramér’s V for categorical variables, and Cohen’s g for paired categorical variables. - **Parameter and Model Standardization**: Tools for standardizing coefficients within and between models, including robust standardization methods. - **Effect Sizes for ANOVAs**: Estimation of Eta-squared (η²), partial Eta-squared (ηp²), generalized ηG², ε², and ω². - **Effect Size Conversion**: Conversion between different types of effect sizes (d, r, Odds ratios, Risk ratios). - **Interpretation**: Convenience functions for applying interpretation rules of thumb, such as Cohen’s guidelines. The package is licensed under the GNU General Public License (v3.0) and is available on GitHub. It is part of the `easystats` ecosystem, which aims to facilitate statistical analyses in R. The package is also used by other R packages like `parameters`, `ggstatsplot`, and `gtsummary` for effect size computation.The `effectsize` package, developed by Mattan S. Ben-Shachar, Daniel Lüdecke, and Dominique Makowski, is designed to estimate various standardized effect size indices and their confidence intervals from a wide range of statistical models. This package addresses the need for assessing the strength of observed associations, facilitating comparisons between predictors, and providing standardized measures that are not tied to the units of measurement. Key features include: - **Standardized Differences**: Functions for estimating Cohen’s d, Hedge’s g, and Glass’ Δ for paired and independent samples. - **Contingency Tables**: Estimation of Pearson’s φ and Cramér’s V for categorical variables, and Cohen’s g for paired categorical variables. - **Parameter and Model Standardization**: Tools for standardizing coefficients within and between models, including robust standardization methods. - **Effect Sizes for ANOVAs**: Estimation of Eta-squared (η²), partial Eta-squared (ηp²), generalized ηG², ε², and ω². - **Effect Size Conversion**: Conversion between different types of effect sizes (d, r, Odds ratios, Risk ratios). - **Interpretation**: Convenience functions for applying interpretation rules of thumb, such as Cohen’s guidelines. The package is licensed under the GNU General Public License (v3.0) and is available on GitHub. It is part of the `easystats` ecosystem, which aims to facilitate statistical analyses in R. The package is also used by other R packages like `parameters`, `ggstatsplot`, and `gtsummary` for effect size computation.