Lab 12: Chi-square and factorial ANOVA

PSY 203: Lab 12.

The primary website for this course is https://faculty.bard.edu/~jdainerbest/psy-203

These are all of the instructions for Lab 12. The list of labs is here.

This website contains R lab code for labs in Bard College’s Fall 2020 for Statistics for Psychology, taught by Prof. Justin Dainer-Best.

You will download the lab’s files to your computer or to your rstudio.cloud account.

Objectives

This lab will walk you through how to plot and run chi-squared (\(\chi^2\)) tests in R, as well as how to plot and run basic factorial ANOVAs. You’ll use the lm() and anova() functions for the latter, much as you did with one-way ANOVAs in lab 9. You’ll use the table() function to create contingency tables and then the chisq.test() function to run chi-squared tests for independence and goodness of fit. You’ll also practice using the {ggplot2} package to create a variety of plots.

Make sure you’re in the right working directory

Set your working directory if necessary. Check that you’re in the directory you expect by running getwd() in the Console. If you need more help, look at the wiki page on setting a working directory.

Today’s lab

To download and then run the tutorial, run the following two commands. Please note: only run the usethis::usezip() line once! Running it again will result in your overwriting the files on your computer—potentially losing your work.

Make sure you run the whole command, all the way to the closing parenthesis.

usethis::use_zip(paste0("https://github.com/jdbest/",
                        "psy-203/raw/master/lab12.zip"), 
                        cleanup = TRUE)
rmarkdown::run("lab12/chisq-and-ANOVA.Rmd")

Once you’ve completed the tutorial, close it and double click on the chisq-F_ANOVA-exercises.Rmd file in the folder you downloaded. (You may need to close the tutorial window.) To work on the exercises with the tutorial running, refer to the instructions on the wiki.