Contingency analysis

Contingency analysis seeks to evaluate a potential relationship between two categorical variables. These data are often visualized as a contingency table.

 
 
An introduction to what statistics is and why we need statistics to answer some biological questions.
 

Contingency Analysis

Contingency analysis is the approach we will use to test whether or not there is an association between two categorical variables. As with the goodness-of-fit test we can use a chi-square test statistic to test our null hypothesis.

Additional Resources

Whitlock & Schluter - The Analysis of Biological Data

Chapter 9: pages 233-254 [Sapling]

Online visualisation by Whitlock & Schluter on the chi-square contingency test

 

Chi-squared test for independence (video 1)

Intro: Video with worked example.

 

Chi-squared test for independence (video 2)

Intro: Examples with graphics and sound effects.

 

Review Questions

 

  1. What statistical test could be used to investigate a potential relationship between two categorical variables?

  2. What are the assumptions of this test?

  3. How is this test different than a goodness-of-fit test?

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