RCPA4 1.0.0

Initial release of the companion R package for Barry C. Edwards and Philip H. Pollock III, An R Companion to Political Analysis, Fourth Edition.

Datasets

• Added six classroom-ready datasets used throughout the fourth edition: anes, gss, states, world, debate, and students.
• Replaced the earlier nes teaching dataset with a curated subset of the 2024 American National Election Study, including documented recoded variables for textbook examples.
• Updated the General Social Survey, state, and world datasets with current observations and expanded political, social, demographic, and economic measures.
• Established maintained metadata sources that generate package data objects, variable documentation, and corresponding textbook appendix material.

Functions

• Updated the package’s teaching-oriented functions for descriptive statistics, data transformation, graphics, confidence intervals, hypothesis tests, comparisons, cross-tabulation, correlation, and regression.
• Improved support for optional sampling weights, data arguments, missing values, input validation, and consistent table and plot behavior.
• Added documented, reusable return values to the principal analysis functions. Regression functions retain standard model behavior, while auxiliary result tables are available through stable names.
• Improved handling of ordered factors and numeric-looking factor labels so that calculations use the displayed values where appropriate rather than internal factor codes.
• Expanded getC() support for common statistical and delimited data formats, compressed files, URLs, and native R files containing one or more objects.
• Redesigned helpC() to provide interactive access to function help, examples, datasets, variable metadata, plotting references, package settings, and chapter resources through R’s configured help system.
• Preserved familiar fourth-edition classroom workflows while improving error messages, P-value formatting, graphics-state restoration, and cross-platform plotting behavior.

Documentation and Testing

• Revised function documentation, argument descriptions, return-value details, and examples to agree with current behavior and use the fourth-edition datasets, including anes in place of nes.
• Updated textbook and online-resource references for the fourth edition.
• Added automated tests for core analysis paths, weighted and unweighted results, return structures, importing, interactive help, plotting behavior, dataset construction, and regression fixes.
• Added a separate checking harness for R code examples used in the textbook so package behavior and book instruction can be reviewed together.