Games-Howell Test (Tukey HSD with Welch's correction for Unequal Variances)
Jun 19, 2019 12:59 PM
Games-Howell Test V1.1.jmpaddin
Enhancements to Version 1.1:
Revamped connecting letters report generation using the insert-absorb algorithm and sweep post-processing algorithm described in Piepho, H.-P., 2004. An algorithm for a letter-based representation of allpairwise comparisons. Journal of Computational and Graphical Statistics 13, 456–466.
Improved handling of excluded groups and missing values.
This add-in allows you to performs the Games-Howell test for one nominal/ordinal group variable and one continuous response. Games-Howell is an adjustment to the Tukey HSD procedure to adjust the error degrees of freedom to account for unequal variances.
Output is similar to Fit Y by X output for the Tukey HSD procedure, which includes the Tukey HSD threshold matrix, Connecting Letters Report, and the Ordered Differences Report. Sample output using Weight vs. Position from the Football sample data set is shown below:
If you get a lot of value from the add-in, please let me know in the comments. If there is sufficient interest, I will work on adding support for multiple X and Y variables, By variables, Weight, etc.