Linked Questions

2
votes
1answer
7k 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 ...
1
vote
1answer
4k views

ANOVA result indicated that there were sig. differences while Tukey post-hoc test revealed that there were no statistically sig. differences [duplicate]

I was conducted one-way ANOVA analysis to examone the level of knowledge shaorng among the employees based on there age differences. One-way ANOVA indicated that there were significant differences in ...
1
vote
1answer
1k views

R Tukey HSD Anova: Anova significant, Tukey not? [duplicate]

i created a simple anova with three groups in R and get a significant Result. After that i do a Tukey HSD Test and now nothing is significant. How can that be? Pr(>F): 0.0316 Group | p adj 1 - 2 ...
61
votes
2answers
23k 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?...
31
votes
3answers
12k 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 report a significant difference when none of the $N(N-1)/2$ pairwise t-tests does? In this answer @whuber wrote: It is ...
7
votes
2answers
23k views

What if an overall ANOVA is not significant, but specific contrasts are?

Study Design: I have a 2x3 factorial design, 2 levels of Time (2050 or 2100) by 3 levels of information (None/Control, Moderate, Extreme). I set up some very specific contrasts when analyzing this ...
4
votes
2answers
1k views

Differing p-values car::Anova, anova & post hoc in logistic regression

I am currently working with a logistic model in R and I have a question regarding the p-values that I get from different types of tests. Since I have separation in my data (caused by X) I use the ...
2
votes
1answer
1k views

Fixed effects contrasts in multilevel model

I'have fitted a mixed model in SPSS with fixed and random effects, and I would like to know what do the Fixed effects contrasts (type III) mean... In my model they are significant (e.g F=23.9; p=.012),...
4
votes
3answers
157 views

Statistically significant difference between distributions only knowing the mean and std dev?

I have 3 specimens (A, B & C) and 5 sets of observations from A & B but only 4 from C. Each set of observations has been reported as a mean & a standard deviation. I do not have access to ...
1
vote
0answers
62 views

Anova() / anova() on a single lme not consistent results - Can you ignore ANOVA?

I am working with the following data: Fixed effect: GROUP (each subject only in one group) CONDITION (within subject variable, there are 2 conditions (1) baseline - same for all the groups, and (2) ...