0
votes
1answer
395 views

How do I interpret the results from the F-test in excel

I have a fairly simple question regarding the interpretation of the F-test in Microsoft Excel. Let't say these are the results of my F-test: http://i.imgur.com/ZLzEQih.jpg I am now wondering how to ...
5
votes
4answers
702 views

Can I do a t test if I have little to no variance in one group?

I have 4 groups that I am comparing to a criterion. In one of my groups, all the participants answered the same on every item, i.e. there is no variance. How do I deal with that in my ANOVA? Also, ...
5
votes
1answer
5k views

Why Levene test of equality of variances rather than F ratio?

SPSS uses the Levene test to evaluate homogeneity of variances in the independent group t-test procedure. Why is the Levene test better than a simple F ratio of the ratio of the variances of the ...
1
vote
1answer
255 views

Choosing N when doing t-tests on bootstrapped samples

Specifically the Welch's T-Test, but probably any T-Test, requires a value for Mean, Variance and N to be used to calculate the T-statistic and the degrees of freedom. I am concerned about these ...
22
votes
6answers
1k views

When conducting a t-test why would one prefer to assume (or test for) equal variances rather than always use a Welch approximation of the df?

It seems like when the assumption of homogeneity of variance is met that the results from a Welch adjusted t-test and a standard t-test are approximately the same. Why not simply always use the Welch ...