Introduction to R
The Statistical Environment
Why R?
R is an open-source statistical software program for data manipulation, graphics, and statistical analysis. It is the program of choice for many statisticians around the world.
Unlike menu-driven software (SPSS, Excel), R is command-driven.
- It is object-oriented (you create and manipulate objects).
- It operates via a Command Line Interface (CLI).
- It has thousands of user-contributed packages (e.g.,
MAd,metafor).
Learning R
- There is a wealth of information online (e.g., R-help mailing lists).
- There are numerous books on R.
- Exercise: Go to DataCamp’s Free Intro to R. Take about 30 minutes to complete Lesson 1 “Intro to Basics”.
The R GUI vs CLI
We will work with both the Command Line Interface (CLI) and the GUI today.
- CLI: Typing commands (Powerful, Reproducible).
- GUI: Menu-driven (Easier for beginners, similar to SPSS).
- We use the MAd package and RcmdrPlugin.MA.
- MAd Package on CRAN
- RcmdrPlugin.MA on CRAN
Basic Operations
At its most basic, R is a calculator.
Vector Operations
R excels at vector arithmetic. You can perform operations on entire lists of numbers at once—a critical feature for meta-analysis where we manipulate lists of effect sizes.
The MAd Package
For this course, we will rely heavily on the MAd package (Meta-Analysis with Mean Differences), which automates many of the complex aggregation and modeling tasks we will cover.
- CRAN Link: MAd Package