Tagged Questions
1
vote
1answer
57 views
Post-hoc for 2x2 mixed design ANOVA using SPSS
I am analysing an experiment run with 20 participants using a 2x2 mixed design ANOVA. The experiment has
one within subjects variable A with two levels (a1, a2)
one between subjects variable B with ...
2
votes
1answer
47 views
How can I perform post-hoc tests to the ANOVA performed during K means clustering?
If I have highly dimensional data and perform k means clustering, I can end up with clusters that differ more on some axes than others.
SPSS provides the option to return an ANOVA for each variable, ...
2
votes
1answer
63 views
Three-way repeated measures ANOVA - what to do next?
I ran a 4(A)x4(B)x2(C) ANOVA in SPSS.
I got significant main effects of A, B and C, and significant interaction effects of AxB and BxC.
I got no significant interaction effects of AxC and AxBxC.
My ...
1
vote
1answer
62 views
Why did I get significant difference result before using post-hoc test but I got an insignificant result after using post-hoc test?
I have done an one-way anova test for to compare among 4 groups. I did the homogeneity test for variance and the result showed the variance was not equal but there was a significant difference between ...
0
votes
0answers
262 views
Calculating Tukey HSD following a repeated measures ANOVA
I was wondering how to calculate Tukey's HSD to follow up a three-way repeated measures ANOVA by hand. I tried to infer how to do it by modifying what I would do in a between subject ANOVA, but I'm ...
1
vote
1answer
304 views
Two questions about Bonferroni adjustment
I have two questions about Bonferroni adjustments:
1). Can one use the Bonferroni method to compare independent groups? The reason why I ask this is it seems that many examples I've encountered ...
0
votes
1answer
93 views
Between group comparison for every level of within factor
If I use lme for mixed ANOVA as follow
...
1
vote
0answers
53 views
ANOVA post hoc with concerned about the sphericity
According to this post the best way to do post hoc analysis in ANOVA in R is t-test + ptukey. Because lme + glht "essentially assumes the sphericity assumption holds".
How are t-test + ptukey ...
4
votes
1answer
411 views
Post-hoc test after 2-factor repeated measures ANOVA in R?
I have problems finding a solution regarding how to run a post-hoc test (Tukey HSD) after a 2-factor (both within-subjects) repeated-measures ANOVA in R. For the ANOVA, I've used the aov -function:
...
3
votes
2answers
342 views
ANOVA results do not match post-hoc Tukey test, how to proceed?
There has been some discussion about why differences exist between factor significance after an ANOVA and no significance in the pairwise comparisons, and it has been very helpful. However, there is ...
0
votes
0answers
497 views
SPSS Anova mixed between-within subjects. Which is the correct way to compare main effects?
I counducted a mixed model ANOVA with time as the within subjects variable (3 levels) and group as the between subjects variable (2 levels). All is significant (time, group, and timeXgroup).
I don't ...
2
votes
2answers
447 views
Anova repeated measures is significant, but all the multiple comparisons with Bonferroni correction are not?
I counducted a mixed model ANOVA with time as the within subjects variable (3 levels) and group as the between subjects variable (2 levels).
All is significant (time, group, and timeXgroup).
To test ...
5
votes
2answers
1k views
Post hoc test in a 2x3 mixed design ANOVA using SPSS?
I have two groups of 10 participants who were assessed three times during an experiment. To test for differences between groups and across the three assessments, I ran a 2x3 mixed design ANOVA with ...
0
votes
1answer
78 views
Post hoc ANOVA following a significant ANOVA?
I am analyzing a data set using a one-way, within-subjects anova with 12 levels. Each of the levels represents a unique trial type in a reaction time experiment. However, the trials can be reasonably ...
1
vote
1answer
172 views
What can I conclude from the following one way ANOVA result?
I used a one-way ANOVA to test if importance levels of attributes have changed over the years (Data comes from a survey of consumers) with the following results (Mean ratings):
...
0
votes
0answers
416 views
pairwise t test or Tukey's test?
I have conducted an experiment with one group of subjects (n=14). I have two within-subjects factors and one dependent variable (called Error). The factor "Type" has 2 levels (Baseline, Operant); the ...
3
votes
0answers
731 views
Non-significant group effect, but LSD post hoc is significant. Why?
I am performing repeated ANOVAs in SPSS and came across something I don't understand.
Basically, the main effect of group (I have three groups) is not significant (p = .062), but the LSD post hoc ...
1
vote
1answer
630 views
Does the Tukey HSD test correct for multiple comparisons?
After performing an ANOVA and then doing post hoc tests with a Tukey HSD test is it still necessary to correct for multiple pairwise comparisons or is that done already?
1
vote
0answers
424 views
Difference between MANOVA “post-hoc” tests of between subjects effects and between subjects one-way ANOVA?
When I run a 2x4x5x6 (Sex*AgeGroup*HighestDegree*Ethnicity) MANOVA (with 20 dependent variables) in SPSS, it presents tests of between subjects effects for each of the IVs and their interactions after ...
5
votes
2answers
5k views
How to obtain the results of a Tukey HSD post-hoc test in a table showing grouped pairs?
I would love to perform a TukeyHSD post-hoc test after my two-way Anova with R, obtaining a table containing the sorted pairs grouped by significant difference. (Sorry about the wording, I'm still new ...
3
votes
1answer
341 views
Use of “post-hoc” tests - do these require an ANOVA to be performed first?
I would like to compare multiple means using a method such as an ANOVA. This would have to be followed up with either Scheffe's test or the Games-Howell post-hoc method (my data is non-normal - to ...
3
votes
2answers
2k views
If only a two-way ANOVA main effect is significant, what is the appropriate follow-up?
What (with justification) is a valid post-hoc for a two-way ANOVA main effect, if no interaction is present?
Example two-way fixed effect ANOVA:
...
5
votes
2answers
2k views
What is a valid post-hoc analysis for a three-way repeated measures ANOVA?
I've performed a three-way repeated measures ANOVA; what post-hoc analyses are valid?
This is a fully balanced design (2x2x2) with one of the factors having a within-subjects repeated measure. I'm ...
0
votes
0answers
404 views
Three-way Repeated Measures ANOVA [closed]
I've posted this question (along with example code and output) at http://www.reddit.com/r/rstats/comments/tglt8/threeway_repeated_measures_anova/
Is this a valid ANOVA model, and are sphericity tests ...
3
votes
2answers
464 views
Best method to visualize large interaction between two factors
In a simple experiment I asked participants to make acceptability judgements (9-point Likert scale) when they observed different animated virtual characters. I have two factors: character (7 levels) ...
1
vote
2answers
862 views
How to report Games-Howell post hoc tests following ANOVA?
I have run a 1 way ANOVA and carried out some post hocs to see which direction the results go in. If I report the direction of the findings - e.g. this group was higher than the other, which statistic ...
4
votes
1answer
96 views
Mean of one group vs. the rest of the sample
I have data from a survey with Likert-type questions (Rate how strongly you feel about this issue on a scale from 1 to 10).
We know the respondents home town (as well as some other information, such ...
4
votes
2answers
529 views
What type of data analysis (ANOVA) should I run on this experiment?
I am not sure how I would analyse this data:
The experiment is looking at the accuracy of emotion recognition in children with ADHD. The children will be asked to identify what emotion a face is ...
5
votes
1answer
382 views
Is it permissible to run post-hoc tests after a non-significant ANOVA?
We ran a 3-way ANOVA getting a non-significant result, but in doing so we saw that one condition looked like it had a strong effect. We tried a Bonferroni-corrected t-test of just that group, and it ...
2
votes
1answer
262 views
Why does post hoc test on pair of group means become significant when looking at subset of levels of factor in ANOVA?
I have something that seems to me an incongruence in ANOVA post hoc tests, and I would like to have an explanation. Basically I performed an ANOVA at the global level on my data and then I performed a ...
2
votes
2answers
5k views
How can I get a significant overall ANOVA but no significant pairwise differences with Tukey's procedure?
I performed with R an ANOVA and I got significant differences. However when checking which pairs were significantly different using the Tukey's procedure
I did not get any of them.
How can this be ...
6
votes
1answer
5k views
Post hoc test after ANOVA with repeated measures using R
I have performed a repeated measures ANOVA in R, as follows:
aov_velocity = aov(Velocity ~ Material + Error(Subject/(Material)), data=scrd)
summary(aov_velocity)
...
3
votes
1answer
3k views
Pairwise comparisons after significant interaction results: parametric or non?
I've run a 2-way ANOVA on growth rate data (grams/day) with the factors of year type (good and poor) and site (A and B). Though the data themselves are non-normal and do not have homogeneous ...
15
votes
2answers
2k views
Do we need a global test before post hoc tests?
I often hear that post hoc tests after an ANOVA can only be used if the ANOVA itself was significant. However, post hoc tests adjust p values to keep the global type I error rate at 5%, don't they? So ...
