"post-hoc" refers to analyses that are decided upon after the data has been collected, as opposed to "a priori".

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posthoc test for a within-subject factor in spss

I am doing MANOVA. I have a within-subject factor "fatigue". One variable is fatigue (baseline, fatigue, rest). One of the dependent variable is the amplitude of swallowing muscle activity (T_tot_d ...
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1answer
32 views

Interpreting a significant 2-way interaction with post-hoc tests

I'm analyzing reaction time data from a repeated measures ANOVA with the following design: Factor 1 (between-group): GROUP (controls, clinical) Factor 2 ...
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14 views

post-hoc test on mixed-effects model

I have an experiment with bacteria for which I measured growth curves of several bacterial clones in two different types of media (treat). I then extracted several growth parameters from the curves ...
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5 views

Chi goodness and Fishers: some theoretical issues post-experiment

I have run a simple experiment under four conditions: the Control, Technique A, Technique B, and Technique C (which is a+b) The dependent variable is compliance (e.g. Yes/No) These are my results ...
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1answer
32 views

Post-hoc Tests for Fisher's Exact Test

I am running a series of Fisher's test to analyse some 2x2 contingency tables with small values. I have found significance. Is there anything equivalent to Cramer's V or the Odds Ratio or some sort of ...
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10 views

Analysis of rates and post hoc test with offset variable using glmer.nb

I am investigating variation in pollinator visitation rate (number of visits per inflorescence) with treatment and time category as fixed factors. Block is a random factor. Following Zuur et al. ...
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10 views

Multiple comparisons with Dunnetts t3 or Dunnetts c

I have a dataset with un-even variance and un-equal class sizes (This was a random sample of land cover classes). After using ANOVA to determine significant differences exist among classes, I ran ...
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11 views

Need help with value for number of measurements and correlation among rep measures in G*Power repeated measures within-between post-hoc

I am looking to find the power of a study using a G*Power post-hoc test for a repeated measures within-between design. I have the effect size calculated, alpha set at .05, my sample size, and number ...
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14 views

All vs all post-hoc after Aligned Friedman (k classifiers over multiple datasets)

I have k classifiers and n datasets, and I have only one accuracy measurement (which is actually the average of three independent repetitions of the 5-fold-CV, i.e. average over 15 accuracy values) ...
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55 views

testing differences between levels of a factor in a linear mixed model

I'm trying to wrap my head around using a linear mixed model and appropriate post-hoc tests to determine if there is a significant difference between various treatments in an experiment I inherited. ...
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37 views

Post hoc tests from Anova() from car-package

I have a small sample unbalanced RCBD, where I have reason to suspect unequal variances, hence I wish to fit a ANOVA with type-3 SS with heterscedasticity consistent esimators. The simplest way to do ...
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1answer
135 views

How to get only desirable comparisons from post-hoc

I have some experimental data that I'm trying to analyze. I have 1 response variable and 3 explanatory variables (these are factor variables). The explanatory variables are the presence of a ...
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1answer
194 views

Games-Howell Post Hoc Test in R

I am doing some data analysis for my masters and I had some data that is normally distributed but does not fit the assumption of homogeneity of variance and has unequal sample sizes. I have been doing ...
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2answers
401 views

Can ANOVA be significant when none of the pairwise t-tests is?

Is it possible for one-way (with $N>2$ groups, or "levels") ANOVA to give a significant difference when none of the $N(N-1)/2$ pairwise t-tests does? Apparently it is possible, but I do not ...
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25 views

Removal of abnormalities in a month-data

I am studying the article Barcelona baby boom: does sporting success affect birth rate?. They are using month-data for their analysis of birth. They have normalised one month to be 30 days. So they ...
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1answer
159 views

Applying a post hoc Wilcoxon signed rank test to a Friedman when there are different sample sizes

I conducted a Friedman test to related-sample group in three conditions (pre-treatment, post-treatment and 6-month post treatment). Out of 216 participants that completed the first two stages, 50 of ...
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1answer
86 views

Is a p-value correction necessary for assessing pairwise location shifts on centered data?

I am currently assessing whether or not a location-shift can be assumed in non-parametric comparisons to be able to formulate the rejection of the null hypothesis in other terms than the probabilistic ...
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2answers
98 views

Running several one-way ANOVA tests on different groups of the same data without inflating type I error

I have 2 categorical independent variables (industry & location) and 1 continuous dependent variable (performance metrics). I need to find significantly different industries by mean performance ...
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82 views

Post-hoc test in the context of cluster analysis

I performed a cluster analysis based on a principal components. Total sample size is around 140. Now I want to describe the differences among the clusters (by means of the components) while performing ...
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1answer
387 views

Significant ANOVA interaction but non-significant pairwise comparisons [duplicate]

I ran a two-way ANOVA and got a significant interaction. I ran a Tukey.HSD() post-hoc test in R and no pairwise comparisons were significant. Is this an error on my ...
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1answer
569 views

How to correctly apply the Nemenyi post-hoc test after the Friedman test

I'm comparing the performance of multiple algorithms on multiple data sets. Since those performance measurements are not guaranteed to be normally distributed, I chose the Friedman Test with the ...
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0answers
49 views

Dependency of a third factor in a correlation between 2 continuous variables?

I'm studying the correlation between 2 continuous variables (A~B), the first is an independent measured variable (A), the second one is a dependent estimated variable (B). I'd like to know i) if the ...
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128 views

Do only certain pairwise comparisons after significant interaction in two-way ANOVA

I am comparing measurements on a test group relative to a control group in three different environmental conditions. I am interested in both differences between environmental conditions and ...
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140 views

Differences between Dwass-Steel-Critchlow-Fligner and Mann-Whitney U-test for a post-hoc pairwise analysis

If you have one control and four groups of patients with a non-normal small sample size, there are differences in these tests for a post-hoc analysis after Kruskal-Wallis?
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1answer
218 views

Post-hoc test in two-way ANOVA

I am doing a two-way independent ANOVA using type of organisational change (5 levels) and job level (7 levels) within the organisation as the factors (in SPSS). I followed Andy Field's procedure ...
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1answer
523 views

Interpreting Two-way repeated measures ANOVA results: Post-hoc tests allowed without significant interaction?

I have conducted a study where I employed a two-way repeated measures design to investigate whether subjects respond to a main treatment effect. What I'm mainly interested in is whether subjects ...
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106 views

Significance difference test between two simple slopes within three level categorical predictor

I've come across related forums, but can't seem to fit them to my problem -- I have significant interaction in a multi-level framework between a three-level categorical predictor (condition ...
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44 views

Split-plot ANOVA

I've carried out an intervention with three groups (control, low practice, and high practice) across two time periods (baseline and post-intervention). I used a split-plot ANOVA to analyse results and ...
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74 views

In SPSS two factor ANOVA, how to compare control groups across other factors?

I have two factors: Brainregion (4 levels) and Group (5 levels). Glutamate is my dependent variable. I am running General Linear Models in SPSS (two factor ANOVA). Can I get the output in such a ...
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15 views

Five different groups

We are running a study which investigates platelet aggregation changes during three trimesters of pregnancy and postnatal period. Then we compare each of these phases to control non-pregnant women. ...
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1answer
417 views

ANOVA interaction term non-significant but post-hoc tests significant

I have animals which took either drug A or drug B (drug factor), and these same animals were either dehydrated or euhydrated (treatment factor). The F-tests for my ANOVA model tell me that only ...
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75 views

Why in this case do the Dunnett's p values are barely any higher than the ones of an unpaired t test?

I was looking at an example from Professor David Howell from the University of Vermont (who I think has recently retired) regarding Post Hoc and Planned Comparison tests. His example entails ...
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1answer
396 views

What are the practical differences between the Benjamini & Hochberg (1995) and the Benjamini & Yekutieli (2001) false discovery rate procedures?

My statistics program implements both the Benjamini & Hochberg (1995) and Benjamini & Yekutieli (2001) false discovery rate (FDR) procedures. I have done my best to read through the later ...
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392 views

Why use ANOVA at all instead of jumping straight into post-hoc or planned comparisons tests?

Looking at a between-groups ANOVA situation, what do you get by actually doing such an ANOVA test first, and second do post-hoc (Bonferroni, Šidák, etc.) or planned comparisons tests? Why not skip the ...
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770 views

2x2x5 repeated measures ANOVA: significant 3-way interaction

I have 3 within-subject factors, namely offset (1px, ..., 5px), side (left, right) and color ...
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761 views

Why do Friedman and Wilcoxon post-hoc contradict each other for my data?

I conducted an experiment, testing three conditions with 27 participants in a repeated measures design. Since the data is not normally distributed I used a Friedman test that reported a p-value of ...
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80 views

Post-Hoc for 2x6 Mixed Design ANOVA

I have run a 2 (gender) x 6 (A) mixed design ANOVA. While I found a main effect for A, the interaction was also significant. While attempting to run post-hoc through SPSS, it said that I was unable to ...
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1answer
154 views

Post-hoc chi-squared multiple comparison tests using complex samples module in SPSS v. 20

This questions refers to computing cross-tabulations and chi-squared tests of independence through the SPSS complex samples module available in SPSS versions 19 and up. I am able to compute the ...
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2answers
6k views

Bonferroni adjustment in SPSS - what does it do?

first post, so go easy... I'm probably being a bit simplistic here, but from what I understand the Bonferroni post hoc test is simply when we adjust the alpha to account for inflated error when ...
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39 views

Is Tukey's Predicted Least Squares an actual test?

A letter in a recent (2011) article of Nature doi:10.1038/nature09817 refers in several places to a Fisher's predicted least-square difference test. A google search returns 102 hits for "predicted ...
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1answer
709 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 ...
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1answer
131 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
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1answer
476 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 ...
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0answers
79 views

Measuring change of participation level in a population after a policy change

I would like to measure the change of a policy in a community, that is, check whether there was a change after the new policy was applied. The old policy required that people had to give away a right ...
2
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1answer
376 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 ...
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1answer
1k views

Post Hoc test for between subject factor in a repeated measures ANOVA in R

I have done an experiment of how different animal species affect nutrient fluxes in sediments. I had a number of experimental units (sediment boxes) to which different animal species were added. I ...
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63 views

Post-hoc analysis when variable effect is non-significant

In a dataset with 3 related measurements for each case, I ran a Friedman test, and found no significant effect. Is it appropriate to now run (and report) pairwise tests, as I had planned initially? ...
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421 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 ...
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1answer
565 views

Comparing groups at different time points within repeated measures study using SPSS

I have done a RCT (randomized control trial) of an intervention (which is of 6 week duration) versus control. The outcome measure (an exercise test) has been tested pre-intervention (Pre), immediately ...
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1answer
1k 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 ...