**Markov Chain Monte Carlo in Item Response Models**, and kindly contributed to R-bloggers)

R is an interpreted programming language that makes it easy to think about statistics instead of thinking about programming. Unlike other programming languages, R is commonly used by typing commands one-at-a-time in an interactive session.

RStudio is a program that facilitates this interactive use of R.

We will use both.

# Getting R

R is free. It is distributed by a consortium that calls itself CRAN (Comprehensive R Archive Network). Many places throughout the world host CRAN content, so getting R is usually quite fast.

R’s homepage is here: https://www.r-project.org/. Feel free to poke around if you like.

To download R, pick the mirror that is closest to you from this list. After selecting one of the mirrors, you’ll get a page that looks roughly like this:

Pick your operating system and follow the instructions to download and install R.

# Getting RStudio

RStudio is also free. It makes it easy to use R for both one-off projects and extended development.

Its homepage is http://rstudio.org/. Feel free to watch their promotional materials and poke around.

The RStudio download page will automatically detect your operating system and suggest the appropriate version. Download the suggested file and install it. All of the defaults will be fine.

RStudio should automatically find your R installation and get you ready to roll.

# Getting used to RStudio and R

There are many resources for learning R. A particularly nice set of tutorials is from OpenIntro. Their labs page looks like this:

Lab 0 offers a concise introduction for a beginner. If you are unfamiliar with R, I suggest working through their first few tutorials.

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**Markov Chain Monte Carlo in Item Response Models**.

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