GPower F-test: Fixed effects, main effects, and interactions in ANOVA

[@Brainbreaker87]

Hi! I have a question regarding your analysis: at 1.50 you show the numerator DF, which are 2 for the interaction or the predictor location. However, in GPower you type in a 3. Why not 2?

[@harmagician1]

Thanks for letting me know. It should be 2 because 3 seating locations minus 1 = 2. I will get this fixed.

[@melissadewit798]

Hello! thanks for this video, it really helps me. There is one thing I don't get; the numerator DF. What is it and it is based on which one, the interaction effect, the location or the gender...???

[@sinadadgar8135]

@@melissadewit798 Melissa, it depends on whether you're looking for the effect of gander or location. If gender, DOF is 1, if location, DOF is 2, and if interaction of gender and location, then the DOF is 2 again

[@InnermostSilence]

@@sinadadgar8135 But am I not looking for effects in general with an ANOVA? I mean, I won't know if there's a main effect or interaction effect before an ANOVA, right? Maybe I'm committing a fallacy though...

[@catstronaut8460]

thank you, this video was exactly what i needed!

[@gabrielcolissi8738]

Thank you so much for your help. You saved me :D

[@floralaura2543]

Thanks very much for this helpful video! I was wondering if you have a citation for the partial eta squared conventions? I am using your demo to inform power analyses for my dissertation proposal and thus, I'd love a cite for that. Thanks again!

[@harmagician1]

+Laura Finch Here is a paper that provides a good description of the differences between eta squared and partial eta squared. www.msu.edu/~levinet/eta%20squared%20hcr.pdf Partial eta squared conventions are tough to nail down. I've searched but have not found any, so my conventions are estimates based on what I've read. If you find any, let me know.

[@rachaeljack1299]

Thanks Dave, this was very helpful!

[@harmagician1]

You're welcome.

[@qianyang2006]

Thanks a lot for this useful video! But I have a question regarding the sample size estimation for 3-way within variables design, what I concern is the 3-way interaction effect, which type of statistical test should I choose for this?

[@konstantinosd.9427]

Dear Davey, Can I use this test in G power to calculate the sample size for a three-way mixed ANOVA with two WS and one BS factor? All have two levels. If not, could you please tell me how to do it?

[@trantoha2023maycuabac]

I'm afrai df = 3 may be wrong, isn't it?

[@harmagician1]

It's wrong. Numerator df should be 2.

[@emmanuelfrimpong9516]

Great!