Unanswered Questions
1,995 questions with no upvoted or accepted answers
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How the Error() term in aov() decides what goes in which stratum?
I am trying to understand how the principles of nested anova in R, but I am having extreme difficulty with the error term.
Imagining the simplest case. I measured plant growth in two places, A and B. ...
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Will Tukey multiple comparison be the same for different types of Sum Of Squares of ANOVA for an unbalanced design
I am working on Two-Way ANOVA for an unbalanced design.
Will Tukey multiple comparison be the same for different types (I, II & III) of Sum Of Squares of ANOVA for an unbalanced design.
I am ...
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Missing cells with Type III SS
I have a linear model of the form y ~ x + z + x:z.
I have unbalanced data and further have a few missing cells (data would be unbalanced even without those missing cells).
My understanding of the ...
CommunityBot
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6
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Posthoc pairwise test on the output of a linear mixed-model (MATLAB or R/Python)
I have observations from three groups of participants (A, B, C), that each represent ratings on three different measures (measure 1, 2, and 3). I would like to know if it is the case that, regardless ...
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How does R's aov function 'work better' with orthogonal contrasts?
The help page for R's aov function states:
The default ‘contrasts’ in R are not orthogonal contrasts, and aov and its helper functions will work better with such ...
- 84k
6
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Orthogonality in ANOVA and Regression Analysis
I read the following (Wikipedia) regarding contrast coding of categorical variables:
Unlike when used in ANOVA, where it is at the researcher’s discretion whether they choose coefficient values that ...
- 84k
5
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Seeking authoritative references on weighted ANOVA
I would be grateful for any reference, such as a textbook or peer-reviewed journal article (of any vintage), that contains explicit formulas for conducting a weighted ANOVA with arbitrary weights.
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- 84k
5
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1
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Randomized Block Design Models
I have been asked to fit the following models in R:
The models are based on this data:
I know the mediums are the blocks and the units of the active ingredient are the treatments. I understand how to ...
CommunityBot
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What is the logic behind ANOVA on ranks?
I've read a few sources that describe ANOVA on ranks, and I am still confused on how the calculation is done, and why.
Specifically:
Is ANOVA on ranks just applying a rank transformation to the data (...
- 1,173
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No value or "."returned for Mauchly's Test of Sphericity in SPSS
I am learning how to do a Two-Way Repeated Measures ANOVA in SPSS but when I try to check the Mauchly's Test of Sphericity Significance value it only displays a single decimal point. It is also ...
CommunityBot
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AIC or ANOVA to compare models?
What are the relative merits of each approach, and which circumstances call for one rather than the other?
To some extent I have a specific example in mind, which I've discussed here. In that example ...
CommunityBot
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5
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How is the confidence interval for variance component in "lmer" function computed by the command "confint"?
Here is the R code :
...
- 1,705
5
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1
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Creating contrast matrix (limma) for two factorial in R
I am attempting to construct a contrast matrix that I can run in R, using the limma bioconductor package, but I am not sure that I have coded the contrast matrix correctly. A previous post and the ...
CommunityBot
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Is Fisher overestimating the variance here?
[NB: the title of this post used to be "Please help me decipher Fisher on ANOVA". I've edited the question to make it more focused, and modified the title accordingly.]
Since anything written by R. ...
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When using repeated-measures ANOVA in R, what does it mean to specify Error(subject) instead of Error(subject/(A*B))?
For a two-way repeated measures design, we can specify the model using aov in the following fashion:
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