PLreg: An R Package for Modeling Bounded Continuous Data

The power logit class of distributions is useful for modeling continuous data on the unit interval, such as fractions and proportions. It is very flexible and the parameters represent the median, dispersion and skewness of the distribution. Based on the power logit class, Queiroz and Ferrari (2023b, Statistical Modelling) proposed the power logit regression models. The dependent variable is assumed to have a distribution in the power logit class, with its median and dispersion linked to regressors through linear predictors with unknown coefficients. We present the R package PLreg which implements a suite of functions for working with power logit class of distributions and the associated regression models. This paper describes and illustrates the methods and algorithms implemented in the package, including tools for parameter estimation, diagnosis of fitted models, and various helper functions for working with power logit distributions, including density, cumulative distribution, quantile, and random number generating functions. Additional examples are presented to show the ability of the PLreg package to fit generalized Johnson SB, log-log, and inflated power logit regression models.