## Repeated Measures ANOVA Problem

Discuss statistics related things

## Repeated Measures ANOVA Problem

I'm trying to run a RM-ANOVA with 8 levels (Repeated Measures Factors) but in the assumptions of sphericity there is an indication reporting that "the repeated measures has only two levels. the assumption of sphericity is always met when the repeated measures has only two levels". However, when I'm running the same test with 7 levels this indication doesn't appear (in the same database). Is this a problem of JAMOVI? If yes, could you fix it?

In case that you need the database, I'd be happy to provide it to you.

Xenophon

Posts: 7
Joined: Fri Mar 29, 2019 3:22 pm

## Re: Repeated Measures ANOVA Problem

In ANOVA, the number of levels a repeated-measures factor has isn't the same as the number of repeat-measures factors there are. For example, a design might have a single repeated measures factor--week--with the eight levels of that factor being Week 1, Week 2, Week 3, Week 4, Week 5, Week 6, Week 7, and Week 8. In contrast, the ANOVA might contain eight repeated-measures factors, with only two levels per factor. Example:

Factor 1: Year (2017 and 2018)
Factor 2: Time of Day (morning and evening)
Factor 3: Nutrient Type (fat and carbohydrate)
[ . . .]
Factor 8: Amount Consumed (low and high).

To do a sphericity test on a particular factor, that factor must have more than two levels.
reason180

Posts: 26
Joined: Mon Jul 24, 2017 4:56 pm

## Re: Repeated Measures ANOVA Problem

I'm running a post-hoc analysis in the RM-ANOVA and the SE and df remain the same in all comparisons. Is this normal?

However, when I'm running the same tests in SPSS or JASP the SE and df are different (JASP and SPSS results in postdoc analysis coincide).
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Xenophon

Posts: 7
Joined: Fri Mar 29, 2019 3:22 pm

## Re: Repeated Measures ANOVA Problem

hi xenophon,

yes, that's normal. the post-hoc tests in jamovi are based on estimated marginal means:

https://cran.r-project.org/web/packages ... asics.html

cheers

jonathon

jonathon

Posts: 841
Joined: Fri Jan 27, 2017 10:04 am