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

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What does a post hoc power analysis say about the significance of the study results?

I orginially posted this over at AskMetafilter, and a commenter suggested I ask it here. I work for a dietary supplement company that also makes skin care products, and some of those skin care ...
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1answer
36 views

Cochran's Q & McNemar tests together

I have binomial outcome data for three groups that I am analyzing with Cochran's Q test. As discussed at this site, Cochran. However, I have to repeat this seven different times because I am ...
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20 views

Post hoc split plot design

I have an experiment in which I have four fenced large plots. I subdived every fenced plot into three smaller fences to have three grazing levels. Within every grazing level I planted 20 saplings ...
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9 views

Obtaining Cohen's d from z-test statistic

After an ANOVA, I run post-hoc tests with the glht function in the multcomp package. glht ...
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12 views

Follow up a significant interaction in ANOVA with dichotomous variables

Hopefully this is an easily answerable question, though I've been searching for an answer without any luck. I've run a 2x2x2x2 mixed-design ANOVA with two within-subjects and two between-subjects ...
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1answer
56 views

Doing post-hoc after a not significant interaction in mixed ANOVA

I conducted a mixed design ANOVA with two within-subjects factors: FactorA (2 levels), FactorB (2 levels), and one between-subjects factor: Group (2 levels). My main hypothesis regards the interaction ...
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19 views

Kruskal-Wallis test for factorial design [duplicate]

Is it possible to use the Kruskal-Wallis test for two factors and their interaction (i.e., two way ANOVA: Y~a*b)? And which post-hoc test is possible to use after ...
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1answer
18 views

R multcomp: contrasts for Tukey

I want to use the glht() function from package multcomp. In the linfct argument, I provide ...
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1answer
43 views

2x2 ANOVA, no main/interaction effects, post-hoc cell mean comparisons necessary/allowed?

I have a 2x2 between-subject design with unequal cell sizes. I ran an ANOVA with type I sums of squares to account for the unequal cell sizes. Neither of the two main effects nor the interaction ...
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2answers
43 views

How to find significant difference in a group/ ANOVA

Am I right to say that the results from the a repeated measures ANOVA does not tell you where a difference is in the group (if any)? So a post hoc test needs to be carried out? I'm using Stata to ...
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1answer
27 views

post-hoc test after logistic regression with interaction. Risk higher for type 1 or type 2 error?

I have a large data set (>1000 obs) and i'm performing regressions tests, both linear and logistic, on a series of clinical outcomes. In this test I verify the effect of interactions between two cat ...
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1answer
30 views

Post-hoc test for slopes - phia package for R

I am trying to do a post-hoc test to make pairwise comparisons between slopes. I found a package called phia but is not available for the R version 2.13.2. Does ...
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1answer
25 views

How to deal with non-normal heterocedastic data from a factorial experiment?

I ran an experiment with two factors each with two levels, 5 replicates each combination and one response variable. My data are non-normal and heterocedastic. Transformations didn't help. I ran a ...
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1answer
59 views

ANOVA and post-hoc analysis using R when we only have means and SD of three populations

I want to perform an ANOVA using R. I have three populations, represented by their respective means and SD: Pop.1: 5.5 +- 0.4 (n=100) Pop.2: 5.9 +- 0.3 (n=150) Pop.3: 6.2 +- 0.5 (n=200) Which is the ...
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24 views

Approach to post-hoc test for factors in a regressions (in R)

I have a problem with some analysis I need to do. I have a series of regressions. Some of the predictors of these regression are categorical with multiple levels. I performed regressions, both linear ...
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0answers
34 views

MANOVA vs repeated measues ANOVA example

I have the following situation (4 independent treatment groups, each group is tested for 3 dependent variables) and was wondering what would be the best to do: What is the best test to do? I have ...
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52 views

R - Post hoc comparisons in 2x2 ANOVA unequal sample sizes

I have a 2x2 between-subject design with (slightly) unequal cell sizes. Hence I chose to use the anova(lm(...)) function so that Type 1 SS are used: ...
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1answer
53 views

Equivalence testing vs ANOVA post hoc tests

How is statistical equivalence testing different from post hoc tests done after ANOVA?
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2answers
87 views

Why test for both correlation and groups differences using the same variable?

A paper asks four research questions which deal with the measurement of latent trait x, a continuous variable which is acquired through learning or practice, and the speed with which the knowledge or ...
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41 views

lme vs lmer vs aov for three factor repeated measures design

I'm trying to run a tree-way repeated measures ANOVA on the following data: I have a completely balanced design with three within-subject factors (type, form and ch - channel) and one dependent ...
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94 views

Post-hoc tests on linear mixed model give mixed results.‏

I am quite new to R so apologies if I fail to ask properly. I have done a test comparing bat species richness in five habitats as assessed by three methods. I used a linear mixed model in lme4 and got ...
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37 views

Post-hoc analysis of 3 sample prop.test

I am looking for the correct way of performing post-hoc analysis on the results of a 3-sample test for equality of proportions and haven't been able to find anything specific to this test. The data I ...
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0answers
25 views

Appropriate post-hoc test after a mixed design anova in R [duplicate]

I have a mixed design ANOVA, with a 2 level between-subject and a 7 level within subject variable. What is the appropriate post-hoc test after a significant ANOVA? I'd like to see R code in the ...
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21 views

Interpreting the results of post-hoc ANOVA

After concluding from a one-way ANOVA, that a variable (country) is indeed statistically significant, I conducted Tukey's multiple comparison post hoc test. Here is the plot for mean Cost (DV) vs ...
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1answer
39 views

Power analysis for post hoc test of ANOVA with many groups

In both G*Power and the R pwr package, estimated sample size required per group decreases as the number of groups increase. This seems somewhat counter-intuitive. For a toy example, assume that I ...
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32 views

Which post-hoc test should I use after finding significance in two-way within subjects ANOVA?

I have tested 3 treatment conditions on 7 scenarios where each scenario had 7 trials (each for 20 subjects). After running an ANOVA (...
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43 views

R: Post hoc tests in ANCOVA with factorial design

Does anyone know how to do post hoc tests in ANCOVA with a factorial design? I have two vectors consisting of 23 baseline values (covariate) and 23 values after treatment (independent variable) and I ...
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35 views

In the output of lsmeans, is “estimate” is effect size of that contrast?

I am using lsmeans to run post-hoc analysis for contrasts of linear mixed model, and here is the output: ...
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11 views

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
124 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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31 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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9 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
186 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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88 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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15 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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15 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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0answers
26 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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96 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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57 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
168 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 ...
2
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0answers
437 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
727 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
226 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
124 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
131 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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119 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
657 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
887 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
54 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 ...