# F-test of equality of variances

Hi all,

I was wondering if there was a way to conduct a Bayesian F-test of equality of variances - I have two groups and I want to show that their variances are equal (H0 is true).

Is there a way to do this with JASP? or R? or any other way (I have a calculator and I'm not afraid to use it!)?

Thanks,

M

## Comments

Hi M,

This is on our to-do list. A recent paper on the topic is here:

http://sci-hub.cc/10.1016/j.jmp.2015.08.001

I'm not sure whether there is R code, but I expect there is.

Cheers,

E.J.

Thanks EJ!

Hi all,

I was wandering the same thing as MSB, and the link E.J. gave is dead now.

I am looking for a Bayesian way to compare hypotheses of equal and unequal variances in two groups in the same way as it is usually done with means (with calculating BF). Does anyone know how to do this in R or in any other software?

Thanks for your help,

Izymil

If you have two groups...one strategy might be to take the F value from the Levene's test...square root it to turn it into a t value...and then use the "summary stats" feature within JASP.

Maybe that is a good approximation (in some circumstances...haven't checked it out) but it's not the real thing (i.e., computing a ratio of marginal likelihoods), and we need the real thing to check whether and under what circumstances the approximation is good.

E.J.