Within subject Anova interpretation, sphericity

[blue]

Dear all!

I have a problem with interpreting my withu+in subjects Anova results.
The sphericity table is not an expected one. I would be very grateful for your help!

Mauchly W is one, approx. chi square 0, df 0, SIgnificance - empty rows, Greenhouse-Geisser Epsilon 1.

Can I report the results using Greenhouse-Geisser Epsilon? It would be important, because the results are good!
Best regards,
blue

[Bruce Weaver]

How many repeated measures factors do you have?  How many levels for each?  How many subjects?  

Have you seen this?

   http://www.talkstats.com/showthread.php/6794-Mauchly-s-test-of-Sphericity-not-defined.-Why

blue wrote

Dear all!

I have a problem with interpreting my withu+in subjects Anova results.
The sphericity table is not an expected one. I would be very grateful for your help!

Mauchly W is one, approx. chi square 0, df 0, SIgnificance - empty rows, Greenhouse-Geisser Epsilon 1.

Can I report the results using Greenhouse-Geisser Epsilon? It would be important, because the results are good!
Best regards,
blue

[blue]

I had two factors with two levels.

Thanks for the link, I have not seen it!

[blue]

Number of subjects 31.

All the best,
blue

[David Marso]

Why would you expect otherwise with 2 levels of the WS factor?
Perhaps review your class notes?

blue wrote

I had two factors with two levels.

Thanks for the link, I have not seen it!

[blue]

I just wanted to check.

[blue]

And we have not dealt with this problem in classes. Sorry to disturb you.

[blue]

Either way, I was trying to get some help, not to be criticized.

[Bruce Weaver]

Thom Baguley's notes on sphericity are good:  http://homepages.gold.ac.uk/aphome/spheric.html.  Look for this heading near the bottom:  Special cases: factors with 2 levels (and the paired t test).

blue wrote

I had two factors with two levels.

Thanks for the link, I have not seen it!

[blue]

Thank you kindly, it will be very helpful!

[blue]

I now finally understand why there is not a problem with my results! Thanks again!

[David Marso]

It wasn't exactly a criticism.  
It was more of a gentle clue stick tap to consider the specifics of your question.
Lacking class notes? Search engines are really useful tools.
I wish they were available when I was green.
All we had were the stacks!
----

blue wrote

Either way, I was trying to get some help, not to be criticized.

[blue]

I have found information on the net and articles, which were not unequivocal.

E.g. some said that the sphericity was violated (with repeated Anova, two factors).

So I wanted to be sure that I am doing the right thing and that I have no mistakes in my work.

The Baguley notes were really helpful in this and I have not found it searching alone on the web!
And I think that these forums are created for information exchange (no matter how "stupid" question is bothering you...)

[David Marso]

I never said your question was stupid!
You might want to become familiar with a forum before stirring the pot.
I've been answering questions here since the early 90's.
Maybe you want to give it a rest!
I think I will close this thread.
---

blue wrote

I have found information on the net and articles, which were not unequivocal.

E.g. some said that the sphericity was violated (with repeated Anova, two factors).

So I wanted to be sure that I am doing the right thing and that I have no mistakes in my work.

The Baguley notes were really helpful in this and I have not found it searching alone on the web!
And I think that these forums are created for information exchange (no matter how "stupid" question is bothering you...)