Linked Questions
14 questions linked to/from How can I get a significant overall ANOVA but no significant pairwise differences with Tukey's procedure?
4
votes
1
answer
9k
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 ...
- 480
1
vote
1
answer
5k
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 ...
2
votes
1
answer
4k
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 ...
- 21
70
votes
2
answers
27k
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?...
- 2,307
35
votes
4
answers
16k
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 ...
- 103k
7
votes
3
answers
1k
views
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 ...
- 128
8
votes
2
answers
28k
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 ...
- 437
4
votes
2
answers
3k
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 ...
- 93
4
votes
3
answers
986
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 ...
- 213
2
votes
2
answers
123
views
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 ...
- 211
2
votes
1
answer
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),...
- 123
1
vote
1
answer
224
views
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 ...
- 63
1
vote
0
answers
97
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) ...
- 15
0
votes
1
answer
33
views
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:
...
- 1