7. Kruskal-Wallis test and Friedman’s ANOVA
Amy Atkinson
This page is under construction for 24/25 and may be subject to change before the teaching week.
Lecture
Watch part 1 here
Watch part 2 here
Download the lecture slides here
Post-lecture activity
Lab preparation
Watch the preparation video here
Download the files discussed in the video here
Lab
Download the lab materials here
Research Question 1
You are a psychology lecturer. You hear that the library is offering three statistics courses. You are interested in whether students who attend the courses perform significantly differently from each other.
You recruit 18 people and assign each one to a course. After the courses are finished, you ask them to write an R script. You time how long it takes students to complete the task. You are interested in whether there is a significant effect of course on the time taken to complete the task.
Research Question 2
You are a developmental psychologist. You are interested in whether working memory develops between 15 and 17 years of age.
You recruit a sample of adolescents and test them on a working memory task when they are 15 years of age, 16 years of age, and 17 years of age.
You then examine whether there is a significant effect of age on working memory score.
A template for running the Kruskal-Wallis test and Friedman’s ANOVA
- Load packages and data
- Normality checks
- Explore your data (e.g. descriptive statistics, a plot)
- Conduct the statistical test
- Conduct post-hoc tests
- Interpret your data
Upload your script
You can upload your finished script for feedback on your code here and feedback will be posted onto Moodle.