All Questions
19 questions
0
votes
0
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17
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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 ...
- 1
0
votes
1
answer
122
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 ...
- 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 ...
- 31
-1
votes
1
answer
49
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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 ...
- 25
1
vote
1
answer
134
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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 ...
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 ...
- 31
1
vote
0
answers
90
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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 ...
- 211
4
votes
1
answer
352
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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.)...
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, ...
- 2,361
2
votes
1
answer
504
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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 ...
- 989
2
votes
2
answers
706
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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 ...
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? ...
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 ...
2
votes
0
answers
665
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 ...
- 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 ...
- 383
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 ...
- 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)' ...
- 51
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 ...
- 791
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 ...
- 19k