# Questions tagged [anova]

ANOVA stands for ANalysis Of VAriance, a statistical model and set of procedures for comparing multiple group means. The independent variables in an ANOVA model are categorical, but an ANOVA table can be used to test continuous variables as well.

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### Nested factorial design for three factors

I want to design an experiment with three factors. Factor 1 shall have two levels (say, A and B), factor 2 has two levels (say, C and D) and factor 3 has two levels (say, E and F). By design, factor 2 ...
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### What approach would you recommend to find the dependent variables that are most affected by the predictors in a multivariate analysis?

I used to handle most of the time species count data. The approach in my group was to do a multivariate analysis of variance, and if there were many dependent variables, we tried to find the ones ...
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### Dropping a condition in a 2 way anova on apex aov_ez

Trying to replicate analysis of a paper. They use 2 way anova with 3x3 design. Except one condition (one cell in the anova matrix) never happens. They specifically say that they use 8 conditions in ...
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### Are the variances in a F-test in Analysis of Variance "nuisance parameters?"

ANOVA estimates 3 sample variances: a total variance based on all the observation deviations from the grand mean, an error variance based on all the observation deviations from their appropriate ...
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### R: Post-hoc tests after ANOVA on mixed linear model give different results, why and how to proceed?

I want to perform an ANOVA test on a mixed linear model. I have variable response "CK" measured in 2 independant conditions: -2 groups of horses (independant variable : Groupe: Groupe 1 and ...
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### Do there exist welch's repeated measures anova/ancova/manova?

Do there exist welch's repeated measures anova,ancova for unequal variances or does one have to run a mixed-effects regression or friedman test? Is it possible to generalize this methodology to ...
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### Model suggestion for zero-bounded dependent variable

I have a repeated measures dataset (8 measurements) with three experimental groups (Randomly generated). The dependent variable (Y) is on a continuous scale bounded inferiorly at 0. I am trying to ...
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### Control differences with dunnett adjustment chart [closed]

Why the answer is A? but store A is not appear in the chart
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### Non-normal distribution in anova - a big problem or not

Please don't close my question, it really is not a duplicate, no other answer on this forum is relevant to my case. Also, I have been advised that if I submit the spss output of my non-normally ...
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### How to summarise ANOVA post-hoc Tukey test?

I am having trouble to interpret tukey's post hoc result from the following They incorporated post-hoc test results into a table using the 𝑎≤𝑏<𝑐 style notation (𝑎,𝑏,𝑐,... correspond to ...
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### What does it mean to do an ANOVA test between more than two groups?

How can you do ANOVA between more than two groups? What would the results of that even mean? As far as I understand it, ANOVA between A and B can tell you if the difference between A and B is ...
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### Statistical test to a large dataset

I have a big dataset with different kinds of human interventions in natural freshwater environments (categorical variable, one column) and the responses as control/ with intervention. It is a reunion ...
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### What does it mean when in a mixed design the "within" subjects is significant only when the "between*within" interaction is excluded from the model?

I have a mixed-design, 1 between (group A and group B) and one within (pre and post). Anova, as well as mixed-effects model, showed non-significant results in the between, in the within, nor in their ...
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### Can I apply ANOVA across dilution factors?

I have 5 flasks. Flask 1 has only water (50 ml). Flask 2 has salt water (50 ml) at a certain concentration (say 10%). I call it dilution factor 1x. For flask 3, I create a 2x dilution solution by ...
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### sum of classic eta squared greater than 1

I know that in an ANOVA with multiple factors (let's say x1 and x2), the sum of their respective classic eta squared (not 'partial' eta squared) cannot be greater than one and should approximate the ...
1 vote
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### How to compare the sensitivity of many countries?

My thesis question is asking whether biodiversity sensitivity differs geographically. I will assess all 5 pressures individually, but take 1 (pollution) as an example. My data contains time series for ...
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### Is it justifiable or acceptable to only check for moderation only in the experimental groups not in the control group

controlled experiment we have 5 groups: 2 Control Groups (CG, passive and active) 3 Experimental Groups (EG, Doseage of the Intervention). We also have two measurement time points T1 and T2 and ...
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1 vote
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### State-of-the-art nonparametric $k$-way ANOVA allowing heteroscedasticity

QUESTION: Can you recommend a nonparametric version of a multiway ANOVA that is also robust in the absence of homogeneity of variances? So, this is what I am looking for: (1) Nonparametric ANOVA (no ...
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### Three versions of the independent two sample t-test (and R)

This post concerns three versions of the independent two sample t-test: Student's t-test uses a pooled standard deviation in the denominator (all equations are shamelessly copied from Wikipedia - ...
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### Question on $2^2$ factorial experiment( replicates)

I am looking at a question, and it seems that the questions is making some assumptions and that they are providing extra information that is not necessary. Here is the question: Consider a $2\times 2$...
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### ANCOVA vs linear mixed model in R, using different functions gives me different results

I have tried different packages, functions, libraries etc in R and my results differ, whether it be p values or F values or DF etc. This is especially true for my within variable (hemi).. between: ...
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### Interpretation of default Type III Sums in Squares in R

Many posts (i.e. here and here) discuss how the Type III sums of squares produced by car::Anova() in R are incorrect or nonsensical under R's default model parameterization, "contr.treatment"...
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### How to find a decomposition of multivariate X along which y varies the most?

I'm looking for an existing algorithm which carries out the task shown in the title. My use-case in other words: I have a set of continuous independent variables (X) and a continuous dependent ...
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### 4 way mixed ANOVA--Need help interpreting a 3 way interaction!

I hope I can clearly articulate my stats troubles! I am having difficulty interpreting findings related to a significant three-way interaction. My study includes one between-subject variable (Group 1 ...
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### unbalanced type II SS ANOVA the correct test?

Good day, I have been pondering over this question for a couple of days now and maybe got lost in the details. I am a Psych Grad student, so my stats knowledge is not as deep as I would wish for. I ...
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### Unsure whether normality is mildy or severely violated, can I still use repeated measures ANOVA?

I am trying to run a repeated measures ANOVA in Stata on a dataset with 149 participants that each gave answers to 4 valuation questions (496 observations in total). I need to measure whether there is ...
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### comparing paired data between two groups

I collected 30 cases of paired data which includes serum creatinine before&after taking specific medication. And the cases are divided into two groups A and B each of which has different medical ...
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### Running robust statistics: trimmed means or bootstrapping?

I am currently running some mixed ANOVAs for a 2x2 design (two groups, with pre- and post- test). Some of my variable are fine, but some of them violate assumptions for parametric testing, e.g. non-...
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### How to find the significance of different levels of an interaction in a generalised linear mixed model?

I am using a glmm to find the effect of lockdown (Yes or No), sex (Male or Female), age (Young, Teenager, Adult) and site (A or B) on hormone concentrations (Continuous). Using lrtest, I have compared ...
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### Residuals of a 2x2 between-subjects factorial ANOVA are not normally distributed

Dependent variable: Emotional impact – measured by two ordinal variables (questions) on a Likert scale [1 (Least) to 10 (Most)] A composite mean score of the two variables was created named ...
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### paired Wilcoxon rank test but with 3 groups

What is the statistical test I should use if I want to run a paired sample Wilcoxon’s signed rank test but I have three groups to compare instead of two?
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### Is it possible to use repeated measures ANOVA with two groups over two time points?

My study design is quasi-experimental. Basically, I am trying to explore the effect of an intervention on two groups of participants (control vs. experiment) over two times (pre- and post-test), and ...
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### Group comparison - aggregate data or compare means?

Let’s say I measure a parameter of interest out of a group of 10 genetically identical individuals (e.g., an inbred C57BL/6J mouse). I can compute a mean, SD or 95% CI from that sample. Then let’s say ...
1 vote
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### Repeated measures anova or ancova ... or other!

I'm working on a trial and would really like some suggestions on how to analyse my data. The study is a randomised crossover trial. I am interested in glucose response to three different lengths of an ...
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### Statistical Significance Testing and PCA Clustering, can I do both?

Is it appropriate to do nonparametric and parametric significance testing on clustered data? More precisely, I performed clustering on PCA dimension reduced data, and created cluster labels for data ...
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### Which statistical test do I use with 2 independent groups and 1 dependent variable

I want to test if there is a difference in the mean distance travelled (Afstand) by sex (Geslacht) and age class (...
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### sample size calculation for 4 groups means

Suppose that I have 4 groups means:18,13,16,10, and 4 standard deviation:10,9,9,8, and α=0.05，β=0.1, how many samples do I need? I'm trying to calculate the sample size using ...
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### Post hoc on mixed model ANOVA with one fixed variable on random independent variable in r

https://www.youtube.com/watch?v=FuiUvwflkVQ In essence, I want to do the exact equivalent to what this video does, but in R rather than SPSS. So far I've used the following code, where DV is my ...
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### Noncentrality parameter Repeated-Measures ANOVA - formula vs. G*Power

I am trying to figure out the correct expression for the noncentrality parameter $\lambda_{ws}$ for the within-subjects effect in a one-way Repeated-Measures ANOVA with $k$ trials/groups. Comparing ...
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### When is single factor ANOVA regression checking out for model diagnostics?

Consider a simple randomized experiment with 4 treatments(no control) where the outcome of interest is difference between pre-treatment and post-treatment count. I want to conclude 4 treatments does ...
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### How to understand the calculations behind a robust mixed factorial function in R, and the implications of running it? Example provided

In "Discovering Statistics Using IBM SPSS Statistics" Andy Field recommends using Robust versions of existing statistics in situations where not all assumptions are met. I'm running a 2x3(...
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### Can I do an ANOVA while controlling for a categorical variable (an ANCOVA except the covariate is categorical)

I'm looking at nesting differences between 3 species of fish. These fish nest in colonies (all 3 species intermix in the colonies), and measurements were taken at several different colonies throughout ...
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### What's wrong with my code for ANOVA test in R? [closed]

Could someone help me see why my code in R does not produce the correct output or do I have a misunderstanding on ANOVA test? As you can see, there are three ...
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### Linear mixed model with unstructured repeated measures

I have a dataset with some growth measurements pre and post vaccination and 3 different groups (3 different types of vaccine) so there are both a within (pre/post) and between factor (group). Problem ...
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### Significant Levene-Test in Mixed ANOVA

I conducted a study to investigate the effect of instagram profiles on mood. Therefore I created two profiles on instagram and used a pre-post-measurement of mood (PANAS-scale). Participants (N=130) ...
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### Which stastical test should I use?

I have 10 participants who were asked to rate (from 1-5) 30 statements. I then asked each participant to assign each statement one of three categories. I want to establish if there is an relationship ...
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### Formal name for research design: repeated measures, 1 varying treatment condition, 1 constant treatment condition

I'm coming from a background with regards to randomizing treatment and just conducting measurement at one point in time. In my current setup, there are just four groups of interest: A control group (C)...