# Helper Functions for Regression Analysis

A set of functions used to automate commonly used methods in regression analysis. This includes plotting interactions, calculating simple slopes, calculating standardized coefficients, etc. See the reghelper documentation for more information, documentation, and examples.

# reghelper

The `reghelper` R package includes a set of functions used to automate commonly used methods in regression analysis. This includes plotting interactions, calculating simple slopes, calculating standardized coefficients, etc.

Version 0.3.3 has been released. However, be aware that this package is still in development, and as such, bugs may still exist, and functions and function parameters may still be subject to change.

To install the most recent stable release, use the following code:

If you are interested in helping out with the development process, you can install the development branch with the following code:

Networked computers can sometimes result in installation issues, as the `install_github` function sometimes has difficulty with networked directories. If this happens to you, use the `.libPaths()` function to find the path to your R libraries. That will likely give you a path starting with two backslashes, but you will need to convert that to a path starting with a drive letter (e.g., 'C:', 'D:'). From there, use the following code:

Obviously, change the path to the path where your R libraries are stored.

## Current progress

So far, most functions that I had originally planned to include have been implemented for `lm` models. These functions include:

• `beta` Calculates standardized beta coefficients.
• `build_model` Allows variables to be added to a series of regression models sequentially (similar to SPSS).
• `ICC` Calculates the intra-class correlation for a multi-level model.
• `cell_means` Calculates the estimated means for a fitted model.
• `graph_model` Easily graph interactions at +/- 1 SD (uses ggplot2 package).
• `sig_regions` Calculate the Johnson-Neyman regions of significance for an interaction.
• `simple_slopes` Easily calculate the simple effects of an interaction.

The table below shows the current types of models for which each function has been implemented:

Function lm glm aov lme lmer
beta
build_model
ICC
cell_means
graph_model
sig_regions
simple_slopes

# reghelper 0.3.3

This is a patch release covering changes necessary to prepare for submission to CRAN. Most changes will not affect current code; however, be aware of the following changes:

• Many of the functions have had the dots parameter (...) added, to ensure consistency with the S3 generic function. However, any extra parameters will simply be ignored. Thus, this does not impact any user code.

• Package functions which implement the following generic methods have had their first parameter renamed, again for consistency with the S3 generic: summary, print, coef, residuals, fitted. In most cases, this will not impact user code, unless you have used named parameters, e.g., `summary(model=results)` should now be `summary(object=results)`.

BUG FIXES

• Fixed bug when using `build_model` but only providing a single model to be run.

• Created special print method for `simple_slopes` so that "lme4" models print correctly.

• Fixed bug (correctly this time) with `simple_slopes` using incorrect contrasts for factor variables.

# reghelper 0.3.2

BUG FIXES

• Fixed bug with `simple_slopes` using incorrect contrasts for factor variables. Resolves Issue #2.

# reghelper 0.3.1

• `build_model` now drops missing data based on the variables included in the final model, so that all models are tested on the same data.

• The `titles` parameter of `graph_model` has been changed to `labels`, and now takes a named list rather than relying on the index of a character vector.

• `graph_model` function extended to include `lme` and `merMod` models.

# reghelper 0.3.0

NEW FEATURES

• `beta` function extended to include `lme` and `merMod` models.

• `build_model` function extended to include `aov` and `glm` models.

• `cell_means` function extended to include `glm` models.

• `graph_model` function extended to include `aov` and `glm` models.

• `sig_regions` function extended to include `glm` models.

# reghelper 0.2.0

MAJOR CHANGES

• Changed `block_lm` function name to `build_model`.

NEW FEATURES

• Added examples to documentation for all functions.

• `beta` function extended to include `glm` models.

• `cell_means` function extended to include `aov` models.

• `ICC` function extended to include `merMod` models (from "lme4" package).

• `simple_slopes` function extended to include `aov`, `glm`, `lme`, and `merMod` models.

• `simple_slopes` now includes `print` function to include significance stars.

BUG FIXES

• Fixed bug with passing variables names to `build_model`, `cell_means`, and `graph_model`. Resolves Issue #1.

# reghelper 0.1.0

NEW FEATURES

• `beta` function calculates standardized beta coefficients.

• `block_lm` function allows variables to be added to a series of regression models sequentially (similar to SPSS).

• `ICC` function calculates the intra-class correlation for a multi-level model (lme only at this point).

• `cell_means` function calculates the estimated means for a fitted model.

• `graph_model` function graphs interactions at +/- 1 SD (uses ggplot2 package).

• `simple_slopes` function calculates the simple effects of an interaction.

• `sig_regions` function calculate the Johnson-Neyman regions of significance for an interaction.

# Reference manual

install.packages("reghelper")

0.3.3 by Jeffrey Hughes, a year ago

Browse source code at https://github.com/cran/reghelper

Authors: Jeffrey Hughes [aut, cre]

Documentation:   PDF Manual