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I have two groups with very small sample sizes. Each group has around 6 observations. I was wondering which test I can use in order to check the quality of variances? Is there any cutoff value in order to compare the variances?

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    $\begingroup$ What do you mean by "quality of variances"? Is there an missing e? $\endgroup$ – kjetil b halvorsen Aug 26 '18 at 15:02
  • $\begingroup$ @user3139228's answer seems like a good start. Can you say more about why you are comparing/testing equality of variance between the groups? $\endgroup$ – Ben Bolker Aug 26 '18 at 15:08
  • $\begingroup$ @ Ben Bolker, thanks for the comment, I want to check the equality of means but first I need to see whether the variances are equal or not. As we have very small sample sizes, is there any cut-off point in order to compare the variances? Forexample if the ratio of variances is more than this cutoff then I could say that the can not be equal. $\endgroup$ – Farid Aug 26 '18 at 16:00
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I have two groups with very small sample sizes. Each group has around 6 observations.

It means that you have a very small statistical power. Your null hypothesis says that both variances are equal. And you have quite a small probability to reject it in favor of an alternative hypothesis even if the null hypothesis is false.

I was wondering which test I can use in order to check the quality of variances?

I think there is no any magic bullet for your problem except trying to increase the number of observations.

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  • $\begingroup$ thanks for the comment. Is there any cutoff for comparing the variances? (Forexample) if the ratio of variances is more than 2 then I could say that the variances are not the same. $\endgroup$ – Farid Aug 26 '18 at 15:20
  • $\begingroup$ The cutoff inversely depends on the number of observations (degrees of freedom) you have. $\endgroup$ – Serhii Kushchenko Aug 27 '18 at 5:52

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