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Can I use both Greenhouse-Geisser AND Huynh-Feldt?

Basically I'm doing a repeated measures ANOVA with the following interactions: Stimulation, Emotion, Time-Stimulation, Time-Emotion, Stimulation-Emotion, and Time-Stimulation-Emotion Mauchly's Test of ...
lou's user avatar
  • 1
0 votes
1 answer
123 views

Is a correction for sphericity violation needed for post-hoc comparisons following repeated-measures ANOVA?

In a repeated-measures ANOVA, there is an assumption of sphericity, so that the variance of differences between groups is similar for all pairs of groups. A violation of this assumption can be ...
Fiona's user avatar
  • 11
1 vote
0 answers
357 views

Variance-Covariance Matrix (Sphericity): Valid?

I am completing a basic statistics exercise for a graduate-level ANOVA course (for psychology trainees). We've just started on repeated measures (i.e. within-subjects) designs, beginning with the ...
Speleo4Life's user avatar
-1 votes
1 answer
49 views

Accuracy vs Precision: Can I use the Sphercity Assumption data in a meaningful way?

I understand that when conducting a repeated measures design with say one factor having three levels (Training: None, Standard, New Method), in the analysis you want the sphercity assumption to not be ...
Hubris555's user avatar
1 vote
1 answer
134 views

How does sphericity violations affect RM-ANOVA results?

My current understanding is that sphericity violations inflate the F-value and therefore type I error. I'd like to know how exactly this manifests itself mathematically. To follow-up, why does ...
Ghislain d'Entremont's user avatar
1 vote
0 answers
166 views

Is sphericity violated if my sample size is less than the repeated measurement count?

In SPSS, I find that the Mauchley's test does not provide any result if the sample size is less than the repeated measurement count. I have a sample size of 19 and a repeated measures of 22. My ...
Srilekha's user avatar
1 vote
0 answers
90 views

Can I use RM-ANOVA with unbalanced within-subject design with sphericity violated?

I have data from an EEG experiment. Originally, the design was balanced, but because in EEG you loose a lot of data to noise and malfunctioning equipment, the end-result is unbalanced data. I am ...
HernanLG's user avatar
  • 211
4 votes
1 answer
352 views

Why is the "sphericity assumption" in RM-ANOVA (constant variance of difference scores) called "sphericity"?

Why is the "sphericity assumption" in RM-ANOVA, i.e. the assumption of constant variance of difference scores, called "sphericity"? (This question was suggested in the comments to a related question.)...
user1205901 - Слава Україні's user avatar
4 votes
1 answer
336 views

Generating a dataset satisfying / violating the RM-ANOVA sphericity assumption

I was reading a research paper where they had a 2x3 repeated measures factorial design with a single DV. A suitable approach to this analysis would be a univariate repeated measures ANOVA. However, ...
Simon's user avatar
  • 2,361
2 votes
1 answer
504 views

HLM vs. repeated measures ANOVA -- sphericity concerns?

All, Say I have a 2 (between) x 4 (repeated measures) mixed factorial design. I was going to analyze it with ANOVA, but normality issues and sphericity concerns have made that not a good idea. Are ...
Tom Carpenter's user avatar
2 votes
2 answers
706 views

Does sphericity (an RM-ANOVA assumption) require the covariances between difference scores to be the same?

Field's Discovering Statistics Using SPSS (2013, Sage) defines sphericity as follows: Sphericity: a less restrictive form of compound symmetry which assumes that the variances of the differences ...
user1205901 - Слава Україні's user avatar
4 votes
1 answer
650 views

Why is compound symmetry sufficient to establish sphericity?

At this website it is stated that "If compound symmetry is met then sphericity is also met." Is it impossible to construct a data set that has perfect compound symmetry but not perfect sphericity? ...
user1205901 - Слава Україні's user avatar
11 votes
3 answers
3k views

Why does repeated measures ANOVA assume sphericity?

Why does repeated measures ANOVA assume sphericity? By sphericity I mean the assumption that the variance of all pairwise differences between groups should be the same. In particular, I don't ...
user1205901 - Слава Україні's user avatar
2 votes
0 answers
667 views

Simulating data for repeated measures ANOVA

I am currently working on a simulation study in which I compare two methods for analysing data from a repeated measures design. Let's say there are n subjects, and each subject goes through i ...
beginneR's user avatar
  • 741
9 votes
1 answer
1k views

Does Greenhouse-Geisser correction influence the effect size estimation, the statistical significance treshold, or both of them? [duplicate]

I discussed recently with one of my colleagues about the Greenhouse-Geisser correction for non-sphericity. I told him first that this correction is very conservative and that it would be more ...
Psychokwak's user avatar
5 votes
2 answers
11k views

Bonferroni and Greenhouse-Geisser corrections with repeated-measures ANOVA

I guess my question comes in two parts: Following a 1x7 repeated-measures ANOVA, I carried out 3 pre-planned tests. Two were t-tests between 2 of the conditions. The third is a 1x6 ANOVA (to test ...
Eric's user avatar
  • 71
5 votes
1 answer
660 views

Issues with the Huynh-Feldt values using either Anova or ezANOVA in R?

Is there an issue with the output of the Huynh-Feldt correction when running an ANOVA for both between and within factors (mixed design) in R? My issue is that when I run a 'within-subject (only)' ...
Sean Estrada's user avatar
3 votes
2 answers
1k views

Whether to use multivariate F test, df adjusted estimate, or sphericity assumed in repeated measures ANOVA?

I have data that involves 2 groups (equal sample size in each) and data for each group over 3 time points (they are actually 3 different monetary reward conditions). I want to investigate within group ...
Short Elizabeth's user avatar
29 votes
3 answers
47k views

Differences between MANOVA and Repeated Measures ANOVA?

What is the difference between a repeated measures ANOVA over some factor (say experimental condition) and a MANOVA? In particular one website I stumbled across suggested that MANOVA does not make the ...
russellpierce's user avatar