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

learn more… | top users | synonyms

6
votes
1answer
181 views

What is the problem with post-hoc testing?

My statistic professor says so, all the books that I look at state it: post-hoc-testing is unscientific. You must derive a hypothesis from theory first, and then collect data and analyse it. But I ...
2
votes
2answers
31 views

Minimum sample size for 1 way ANOVA?

I have tested a group of participants over various time points and I want to investigate whether mean score on each subsequent time point is significantly different to the mean score at baseline (eg. ...
0
votes
0answers
8 views

post hoc nested

Hy, need to do post hoc test for nested factor in SAS. I have two factors, A and B with B nested within A and I want to perform post hoc test in GLM in SAS. Is it possible? Stevan
0
votes
0answers
17 views

What type of post hoc test does a LME use by default?

I need to know what type of post hoc test a LME model is using in R, by default? Is it Tukey? And is the alpha modified?
2
votes
0answers
49 views

Converting Chi Square Adjusted Residuals to p values

I am running a chi squared analysis in SPSS on a 5 x 2 contingency table. The overall chi square p value was < 0.0005, so I ran post hoc tests (adjusted standardized residuals on the individual ...
0
votes
0answers
11 views

One way ANOVA: post-hoc comparison “adding letters to graph” [migrated]

I am working on a project for one of my classes and cannot figure out how to obtain the letters for treatment comparisons after using the tukeyHSD post-hoc test. Is there a simple way to do this? ...
0
votes
0answers
23 views

What is the relationship between degrees of freedom and number of comparisons in Nemenyi's post hoc test?

I have some data consisting of non-normally distributed samples drawn from one of several different groups. A Kruskal-Wallis 1-way ANOVA rejects the null hypothesis that the medians of the groups are ...
2
votes
1answer
16 views

Can I justify using a one-tailed test in for this interaction effect?

I have an experimental setup with 2 factors, site and disturbance treatment. I have reason to suspect that plots at site A will be more affected by treatment than plots at site B. My response ...
0
votes
0answers
42 views

When an effect size has to be considered sufficiently large?

I submitted a paper in which I analyzed the data by a mixed design ANOVA. I reported generalized eta squared as effect size. After significant interactions, I conducted planned comparisons. A reviewer ...
0
votes
1answer
45 views

Post Hoc test after lme [closed]

I am trying to run a Post Hoc test (glht) after a linear mixed model (lme) in R. I was ...
3
votes
1answer
44 views

Post-hoc after GLM: What does it exactly say?

Background: I have been asked to model the change of weight of a few animals undergoing experimentation via a simple GLM (General Linear Model). The data looks something like this. Note that all data ...
0
votes
0answers
29 views

How does one do a Post-hoc test for a Poisson glm in R?

My data consists of the following categories: Site - 3 sites - Boulder, Rubble and Cul-de-Sac Season - 4 types - warm1, warm2, cold1 and cold2 Behaviour - 6 behaviours scored - Basking, ...
0
votes
0answers
27 views

Post-hoc with Bonferroni a correction after ANOVA with repeated measure in SPSS

does somebody know where I can find the t value of post-hoc tests with Bonferroni correction when using SPSS.From what I get so far, I only see p values. Should I add a command in the script? Thank ...
0
votes
3answers
60 views

Testing and reporting interactions in multiple regression

I have a model with two between-participants predictors -- one continuous (a), and one categorical with two levels (b) -- and ...
0
votes
0answers
30 views

Can one make a Tukey post-hoc test for multiple regression in R and how?

I saw that the Tukey post-hoc test is usually done after performing an ANOVA. However, is it possible to carry it out in the case of multiple regression with the following model: ...
3
votes
0answers
28 views

Post-hoc power analysis of complex sample survey data

I am working with a complex sample survey data using Stata to determine the predictors of a given dependent variable. As part of my analysis result I want to report the post-hoc power for each ...
0
votes
0answers
15 views

Pairwise comparison of slopes from multivariate regression model in R

I am investigating size changes over time. I have five size variables in a multivariate linear model against year. I used the Anova() function in the car package to test whether the slopes are equal ...
0
votes
0answers
9 views

Follow up 2-way ANOVAs

I have a three-way significant interaction in a mixed-ANOVA, with two repeated-measures factors and one between-subjects factor. I would now like to follow it up with a repeated-measure ANOVA for each ...
0
votes
0answers
28 views

Post hoc for GLM that looks at interactions (in R)

I’d like some help with analysing some count data. I am very new to R (and statistical analysis for that matter!) and have done my best to work it out on my own … but seemed to have got stuck! I am ...
0
votes
0answers
29 views

How to use controls as a reference in GLM?

I'm running glms in R on two datasets, both with three discrete explanatory variables and one continuous dependent variable. My question is about the use of controls - I want to use my controls as a ...
0
votes
0answers
43 views

mixed design and simple main effect analysis in SPSS

Hope someone can help me. I have a within subject variable (Question, with 11 conditions) and a between subject variable (stimulation, with 3 conditions). I did an ANOVA and I obtained a main effect ...
0
votes
1answer
72 views

Which post-hoc is more valid for multiple comparison of an unbalanced lmer-model: lsm or mcp?

After doing a model comparison with my mixed lmer model, I have a model with three main effects, no interaction, say ...
0
votes
0answers
41 views

How do I report the result of an mcp-Tukey-test, i.e. how do I report it's z value?

After doing a model comparison with my mixed lmer model, I have a model with two main effects, no interaction, say signal ~ factor A + factor B + (1|subj). Factor ...
0
votes
0answers
39 views

GEE and post hoc comparisons

I am trying to analyze a dataset using the GEE. This is what I have so far ...
0
votes
0answers
35 views

Looking for a better post-hoc analysis

I'm a PhD student in Neuroscience, with a master degree in Psychology and I use R for my statistical analyses. As you know, in NHST usually post-hoc analysis in continuous data are essentially ...
0
votes
1answer
114 views

F stats for post hoc test of a linear mixed effects model

I have an unbalanced linear mixed effects model with three fixed factors of various levels and one random factor for my repeated measures data (for details see here). Thanks to your help I managed to ...
1
vote
2answers
49 views

Post hoc Scheffé test

My 1-way ANOVA test is not significant. Is it possible that a Scheffé test as a post hoc test be significant? If not, please say why not.
0
votes
1answer
69 views

Appropriate non-parametric post-hoc test for baseline comparisons?

I want to evaluate several "classifiers" (machine-learning algorithms) with paired samples. I do not want to compare each algorithms' performance to every other (n x m comparison) but only compare the ...
0
votes
1answer
33 views

Refitting with different contrasts vs. pairwise comparisons

Say, I fit a linear or generalised linear model in R with dummy coding (contr.treatment for ...
0
votes
1answer
34 views

Effect sizes for post-hoc paired comparisons in one-way ANOVA

Is there any alternative (like Cohen's d in t-test) to report about effect sizes for post-hoc paired comparisons in a one-way ANOVA (3 factor levels, correlated samples)?. Many thanks!!
1
vote
1answer
79 views

Mixed ANOVA post hoc analysis (and multiple comparisons)

I have a set of 12 subjects: 6 administred with drug A and 6 with drug B. For each subject two time-points have been collected (before and after drug treatment) for each analyte (over 6000). I had a ...
0
votes
2answers
129 views

Post-hoc tests for 2x2 ANOVAs (Type II & III) with interactions in R

I am trying to analyze data from an experiment using R and ran across a problem regarding the use of post-hoc tests with Type II & III ANOVAs. I only know of R functions that perform post-hoc ...
3
votes
1answer
37 views

GLM post hoc with non-parametric tests?

I have a question regarding the appropriate use of comparisons for independent samples (3 factor levels). Overall sample size is N=546, subsamples: 218 or 228 or 100), convenience sampling, ...
1
vote
1answer
167 views

Standard error bars overlap but significance - estimated marginal means versus observed means

I'm running a Mixed effects model ANOVA with two fixed factors (condition, repetition) and one random factor (subject). Subsequently, a Tukey multiple comparisons test is performed. Now I'd like to ...
2
votes
1answer
96 views

Post hoc test other than Tukey for factorial ANOVA data in R

I am looking for help on post-hoc tests of my group data (treatment and stage and interaction) after running a 2 way ANOVA in R. The data shown below is an example only. Actually my data shows ...
0
votes
0answers
26 views

Multiple comparisons, multidimensional data, several groups

Could you please help me with such a problem: Let's assume I have multidimensional data that consists of 30 samples and 10 variables. This is a 30x10 matrix. I have three groups of equal size (10 ...
2
votes
2answers
122 views

Post hoc test for object of class glmerMod in R?

I am running generalised linear mixed effects models in R using the lme4 package. I am wondering if there are any post-hoc tests available for models built using the glmer function? I know the ...
4
votes
2answers
77 views

Why is the Bonferroni correction properly used with planned, and not post hoc, contrasts?

The Wikipedia article on Post hoc analysis says "Bonferroni correction (This is properly used with planned, not post hoc, contrasts.)" but does not explain why the Bonferroni correction is properly ...
1
vote
0answers
51 views

Which post-hoc comparison to use and why

Hopefully this is now a much clearer picture of the question I want to answer: For each of 60 different plans I ran 35 simulation replications of my Agent Based Model (ABM) simulation. Then for each ...
1
vote
1answer
57 views

Post hoc selection of important features in random forest?

I want to guarantee a parsimonious random forest (few features used). What are methods to do this? It was suggested to me to get the feature importance after the model was created, and then create a ...
2
votes
1answer
146 views

Post hoc $\chi^2$ test with R

This is a quite simple question but I don't find any good, clear, precise answers: I'm looking for a way to perform post hoc test on a chi$^2$ test. I have 2 variables : var1 : good/fair/poor and ...
3
votes
2answers
442 views

Can Mann-Whitney test be used for post-hoc comparisons after Kruskal-Wallis?

I have a simulation where an animal is placed in a hostile environment and timed to see how long it can survive using some approach to survival. There are three approaches it can use to survive. I ran ...
0
votes
1answer
127 views

$\textit{Post hoc}$ test after repeated measures ANOVA (LME + Multcomp)

I have a dataset where the samples are dependent, belong to different groups, and measurements were taken over time. It looks like this: Subject Group Time Value S1 G1 12h 5.55 S1 G1 24h ...
0
votes
0answers
40 views

How can I perform a post hoc test of a three-way interaction in SPSS using the 'test' command?

I will describe the design of the experiment briefly. The task have two within-subject variables ($A$ and $B$), A. have two levels B. have three levels one repeated variable with 5 levels ('time ...
0
votes
0answers
112 views

How to test signicance of differences between factor levels in mixed model using lme4 in R

My basic knowledge on model simplification comes from Crawley (2007) and I have also looked in Zuur et al Mixed Effects Models and Extensions in Ecology with R to try to answer my question. In ...
2
votes
2answers
273 views

Post-hoc tests for MANOVA: univariate ANOVAs or LDA?

I am using a MANOVA test to compare nine different dependent variables (from neuropsychological and neuropsychiatric assessment) between three groups. The output shows a significant influence from ...
0
votes
2answers
110 views

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 ...
1
vote
1answer
195 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 ...
0
votes
0answers
44 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 ...
0
votes
0answers
35 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 ...