Linked Questions

4 votes
1 answer

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 ...
Mina's user avatar
  • 480
1 vote
1 answer

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 ...
Yasser Al-Qadhi's user avatar
2 votes
1 answer

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 ...
Robinator's user avatar
70 votes
2 answers

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?...
even's user avatar
  • 2,307
35 votes
4 answers

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 ...
amoeba's user avatar
  • 103k
7 votes
3 answers

Why does $\mu > 0$ (or even $\mu > \epsilon$) "seem easier” to substantiate than $\mu \neq 0$?

Consider a random variable $X$ following a normal distribution $N(\mu,\sigma^2)$. Suppose that we have drawn iid samples of $X$, obtaining a data set with a sample mean $\bar{x}>0$. We want to test ...
Nuno's user avatar
  • 128
8 votes
2 answers

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 ...
Lee's user avatar
  • 437
4 votes
2 answers

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 ...
mela's user avatar
  • 93
4 votes
3 answers

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 ...
DrBwts's user avatar
  • 213
2 votes
2 answers

Formal definition of p-value [duplicate]

Could you provide formal definition for p-value? Or, do you have any good source for it? For a day, I've been searching for the formal definition of p-value, but I couldn't yet. The majority of the ...
orematasaburo's user avatar
2 votes
1 answer

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),...
Mike_999's user avatar
  • 123
1 vote
1 answer

qqplot result and normality for ANOVA

The independent variable is promotion, and it is assigned to 3 groups. The dependent variable is sales revenue. I have 172 observations of sales revenue for promotion group 1, 188 for group 2 and 188 ...
Dan K's user avatar
  • 63
1 vote
0 answers

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) ...
Karvin's user avatar
  • 15
0 votes
1 answer

Significant ANOVA interaction but non-significant pairwise comparisons while doing meta-analyses with metafor R

This is the regression result and it contains the omnibus tests which is quite significant. Multivariate Meta-Analysis Model (k = 158; method: REML) Variance Components: ...
Dips's user avatar
  • 1