Homogeneity of Variance

1 / 3

Homogeneity of Variance - PowerPoint PPT Presentation

Homogeneity of Variance. Pooling the variances doesn’t make sense when we cannot assume all of the sample Variances are estimating the same value. For two groups : Levene (1960): replace all of the individual scores with either then run a t-test. or. F - test.

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

PowerPoint Slideshow about 'Homogeneity of Variance' - susane

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -
Presentation Transcript
Homogeneity of Variance

Pooling the variances doesn’t make sense when we cannot assume all of the sample

Variances are estimating the same value.

For two groups:

Levene (1960): replace all of the individual scores with either

then run a t-test

or

F - test

Given: 1. Random and independent samples

2. Both samples approach normal distributions

Then: F is distributed with (n-large-1) and (n-small-1) df.

Null Hypothesis:

Alternate Hypothesis:

K independent groups:

Hartley: If the two maximally different variances are NOT significantly different,

Then it is reasonable to assume that all k variances are estimating the population variance.

The average differences between pairs will be less than the difference between the smallest

And the largest variance.

A and B are randomly selected pairs.

Thus:

will NOT be distributed as a normal F.

(k groups, n-1) df

Then, use

Table to test

Null Hypothesis:

Alternate Hypothesis:

Looking at the correlation between the variances (or standard deviations)

And the means or the squared means.

b) Use square root transformation

c) Use logarithmic transformation

d) Use reciprocal transformation