The metafor package in R provides functions for conducting meta-analyses, including fixed- and random-effects models, and allows for the inclusion of moderator variables. It supports meta-regression with continuous and categorical moderators, and includes functions for the Mantel-Haenszel and Peto's one-step methods. The package also offers plot functions for forest, funnel, and radial plots, as well as tools for assessing model fit, case diagnostics, and publication bias tests. The metafor package is designed to handle moderator analyses more comprehensively than other R packages, enabling users to fit meta-regression models that examine the influence of one or more moderator variables on outcomes. The package includes functions for calculating various effect size measures, such as odds ratios, relative risks, risk differences, and correlation coefficients, and supports both default and formula interfaces for data input. The package also allows for fitting mixed-effects models with categorical moderators, and provides tools for testing the significance of moderators and adjusting for uncertainty in the estimation of heterogeneity. The metafor package is widely used for conducting meta-analyses in R, offering a flexible and powerful tool for researchers in various fields.The metafor package in R provides functions for conducting meta-analyses, including fixed- and random-effects models, and allows for the inclusion of moderator variables. It supports meta-regression with continuous and categorical moderators, and includes functions for the Mantel-Haenszel and Peto's one-step methods. The package also offers plot functions for forest, funnel, and radial plots, as well as tools for assessing model fit, case diagnostics, and publication bias tests. The metafor package is designed to handle moderator analyses more comprehensively than other R packages, enabling users to fit meta-regression models that examine the influence of one or more moderator variables on outcomes. The package includes functions for calculating various effect size measures, such as odds ratios, relative risks, risk differences, and correlation coefficients, and supports both default and formula interfaces for data input. The package also allows for fitting mixed-effects models with categorical moderators, and provides tools for testing the significance of moderators and adjusting for uncertainty in the estimation of heterogeneity. The metafor package is widely used for conducting meta-analyses in R, offering a flexible and powerful tool for researchers in various fields.