10
votes
What is the reason behind the name "adonis" (for permutational MANOVA)?
Actually it isn't -- the statistical method is not called adonis.
The authors of the vegan software package for R (http://vegan.r-forge.r-project.org) implemented the statistical procedure you refer ...
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6
votes
Discriminant Function Analysis in SPSS: Sorts effectively, but Box's M is still 0.000. Is the analysis worthless?
Box's M test is to check if the groups' covariances matrices are the same in the population; this homogeneity of covariances is as assumption of linear discriminant analysis (LDA). The test is quite ...
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5
votes
Accepted
Why does MANOVA report values of F-statistic in addition to Pillai/Wilks/Hotelling/Roy?
The primary test statistics are the four values given: Pillai's trace, Wilks' lambda, Hotelling's trace and Roy's largest root. The distribution of each of these is, in general, complicated and so ...
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5
votes
How to interpret type I, type II, and type III ANOVA and MANOVA?
For illustration I assume a two dimensional ANOVA model specified by y ~ A * B
Type I ANOVA
Line term in ANOVA table
Hypothesis from model
Hypothesis to model
A
y~...
- 843
5
votes
Accepted
What is the reason behind the name "adonis" (for permutational MANOVA)?
I am the culprit and this is my true confession: it was Hank's idea (Martin Henry H. Stevens). We already had a function called anosim (Analysis of Similarities, of Primer strain) in vegan, and even ...
- 661
4
votes
Accepted
How is MANOVA a case of the GLM?
Just as t-tests and ANOVAs are special cases of the univariate general linear model (as you show in your question), the univariate general linear model is also just a special case of the full general ...
- 2,225
4
votes
MANOVA as protection against Type I errors
Requiring a significant MANOVA or ANOVA before conducting individual t-tests can help protect against Type I error, but is not generally sufficient to provide strong Type I error control. For example, ...
- 369
4
votes
Accepted
What is the explanation of the difference caused by the order of variables in anova for the concrete example in R?
When you call anova on an lm model fit, under the hood you are really using ?anova.lm, which ...
- 155
4
votes
MANOVA with variables from different datasets
One option here is to think of this as a missing data problem. You have varying amounts of information for each case (different tree species) that you have classified as one of five different species. ...
- 2,184
4
votes
Is it okay to perform PerMANOVA on PCA values?
I will leave it to others to decide if a permutational multivariate analysis of variance on principal components is 'acceptable' to them. But there isn't any logical error in computing such a ...
- 9,552
4
votes
Accepted
What analysis is best with a binary independent variable that is very skewed?
This is not an issue at all and your analysis should not change based on the distribution of this variable. A regression model with event, your moderator, and their interaction would be sufficient. I ...
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3
votes
Accepted
Why is it rarely reported in papers which type of sums of squares is used in Anova results?
This is not an easy question to answer (at least for me) but my guess is that the great majority of people go with the default settings of the program that they are using (irrespective of whether this ...
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3
votes
Why is Pillai's trace equal to partial eta squared in a repeated measures MANOVA (profile analysis)?
The short answer to your question is...
... in a multivariate context, there is much less of a distinction between hypothesis test statistics (e.g. F in a univariate context) and effect size ...
- 2,225
3
votes
Should I use MANOVA, ANOVA for Regression?
It sounds more like a multiple regression question.
All three of MANOVA, ANOVA, and regression fit into the heading of the general linear model. ANOVA is a special case of the linear model where you ...
- 849
3
votes
Within-Subjects or Between-Subjects MANOVA
The error term will typically be lower when between-subjects variance is removed from error as it is in within-subject designs but not in between-subjects designs. As is often said: subjects are their ...
- 1,374
3
votes
Accepted
A is correlated with B/ A has an impact on B
Counterexample: Acne causes kids to start middle school.
No...they simply happen to coincide because both occur around the time kids are 10-12 and therefore starting middle school.
This is true for ...
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3
votes
Accepted
Is this a proper use of mixed modeling?
The model you are thinking about:
Area ~ Peptide + ( Peptide | Reaction_Time )
doesn't really make sense. The primary interest is in the association of reaction ...
- 63.9k
3
votes
Treat year as a fixed effect, random effect, or covariate?
First note that including a variable as a covariate and as a fixed effect means exactly the same thing to the model.
So the question is about whether to include year as a fixed or a random effect. I ...
- 63.9k
3
votes
Accepted
Replicating an SPSS manova in R
I am not very familiar with SPSS but as far as I see MANOVA in SPSS reports multivariate tests for each predictor separately (just like manova in R). So, it does ...
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3
votes
If data is square rooted to assume normality, should the data used to test with Levene's Test for Equality of Variance also be square rooted?
If you do the equality of variance test for the purposes of assumptions of manova, you need to test the data on the scale you will use in the manova.
Presumably (after what you told us) that is the ...
- 81.7k
3
votes
Excluding participants due to issue in randomisation?
Equal group size is not a requirement for anova (it might be an advantage if you can have it). So, as long as group assignment is still random and representative, as you say it is, there is no reason ...
- 81.7k
2
votes
Significant output in Levene's test for equality of variances in MANOVA; what to do?
First, make sure you look at the boxplots of the residuals instead of just using Levene's tests. The significant result could be due to outliers, a bimodal distribution, or skewness that you may need ...
- 646
2
votes
Does one need to adjust for multiple comparisons when using MANOVA?
There's no need to adjust the alpha level of the MANOVA test itself, as amoeba noted. However, a significant MANOVA doesn't allow you to make statements about any of your 10 DVs--that would require ...
- 369
2
votes
Accepted
Transformations possible when performing a single multivariate ANOVA on a continuous and categorical species database?
For the record, after discussions with other colleagues, I believe since my species in categories (from 0 = absence to 4 = 75-100% cover) are somewhat already transformed, the best way will be square ...
- 535
2
votes
Pros and cons of 5 ANOVAs for 5 DVs instead of 1 MANOVA
It depends on what the research question is. Multivariate analyses help to answer the question "Is there a main effect on any of these DVs?". So, if there's no theory-driven prediction on any ...
- 368
2
votes
Repeated measures analysis of mutually correlated features
You might consider a repeated-measures MANOVA. The MANOVA is analogous to the ANOVA, but with more than one dependent variable. Just like the ANOVA, you can have several independent variables (...
- 843
2
votes
What is the explanation of the difference caused by the order of variables in anova for the concrete example in R?
I like to understand linear regression in terms of its computation. A linear model is computed by QR factorization, giving a number of "effects" on the rotated plane. You can refer to What is the “...
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2
votes
Why is Pillai's trace equal to partial eta squared in a repeated measures MANOVA (profile analysis)?
Let - considering MANOVA with one factor with $k$ groups, for simplicity - $\bf B$ be the between-groups scatter matrix and $\bf W$ be the pooled within-group scatter matrix. (Please see "Bonus" ...
- 58.4k
2
votes
Should I use MANOVA, ANOVA for Regression?
The difference between ANOVA and MANOVA is merely the number of dependent variables fit. If there is one dependent variable then the procedure is ANOVA, if two or more dependent variables, then MANOVA ...
- 13.2k
2
votes
Is there a non-parametric equivalent of factorial MANOVA (at least 2x2)?
As far as I know there is no non-parametric equivalent to MANOVA (or even ANOVAs involving more than one factor). However, you can use MANOVA in combination with bootstrapping or permutation tests to ...
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