Equivalence of standard deviations with different sample sizes

Question

A customer is looking into understanding testing for equivalence for standard deviation. The help documentation is a bit confusing on testing for equivalence for standard deviation and there is no example (only for equivalence of means).

Does anyone have a good example of this?

Also, how does sample size affect this test? The sample sizes are quite different, without knowing what "quite" means specifically. S

And, to follow up on the sample sizes, how do unequal sample sizes come into play in, for example, the unequal variance test, Welch's test for means with unequal variance, the Games-Howell test (found through the add-in for a comparison of more than 2 means with unequal variances) and the equivalence of means test?

monique_lander · Answer

I forgot to look in the training starter! Would be great to have an example in the JMP documentation for customers as well.

Jed_Campbell · Answer

I use the Process Phases data table from the Training Starter (JMP 17 > JMP > Equivalence Improvements). The scripts saved to the data table seem to make sense when shown in order.

rsdeshpa · Answer

Games-Howell test is a non-parametric test equivalent to Tukey Kramer. It works well when the variances are unequal.   Kruskal-Wallis test is a non-parametric equivalent to ANOVA.  These are good options for unequal variances. However, non-parametric tests usually require all groups to have large sample sizes.

I found this example for interpreting equivalence test for variances (test is for variance instead if standard deviation).

Example of the Unequal Variances Option