1.1 What is R?

First, R is a programming language. If you write code in R and save it, it will remain useful and repeatable for as long as you have a program that can run your code, which brings us to the second layer. R is a code interpreter (otherwise known as software). You can run R at the command line and either enter code directly, or tell it to run code files, or scripts, that you saved earlier in order to analyze data, run simulations, or anything else R can do (for example, produce this Tutorial).

• You can download R from the Comprehensive R Archive Network.

Finally, RStudio is an excellent (and constantly improving) GUI (and development) interface for R, providing point and click access to many common tasks, and easy access to script files, help and documentation, plotting, copying and saving figures, code autocomplete and syntax help, and many other useful features.

• You can download RStudio from www.rstudio.com.

It is important to also note that R is free and open source. This means that you can learn and use this fully featured statistical computing framework, and continue to use it for free after you finish this class, and beyond. Additionally, R is incredibly extensible. When someone comes up with a new method, they (or someone who wants to use it in R) will often implement the method as a collection of functions in R called a package.