# 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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### Compute marginal means and effect sizes with a fixed effect linear model with repeated measures

I am trying to better understand the relationship between linear models and ANOVA by doing it a bit more manually. To do this: I create a toy dataset, with two categorical variables, which I consider ...
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### What is the best test to run to compare presence/absence of something between sampling locations?

I have data on the presence/absence of four different pathogens found in edible crabs in 7 locations over 2 seasons. For this study, 30 crabs were collected from each site and for each crab the ...
1 vote
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### How to interpret two way ANOVA repeated measurements results?

I measured the percentage of individuals that crossed a barrier at six different time points for four different genotypes (e.g for replicate 1 of genotype 1: at 0h 0/20, at 0.5h 19/20 etc. animals ...
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1 vote
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### Two-Way ANOVA or Mixed model

I have a dataset organized with time points on the x-axis: baseline (0 days), 3, 7, 14, 21, and 28 days. These time points correspond to periods where I measure deficit scores (y-axis) in animal ...
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1 vote
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### Two-Way repeated measures ANOVA with multiple data points per measurement

I would like to perform a study with physicians of three levels of experience. They shall perform a task under three different conditions. For each condition, the task is performed multiple times (e.g....
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### Can descriptive statistics of three ordered groups be converted into a correlation?

I know that a one-way ANOVA with two groups can be converted into a Standardized Mean Difference (SMD), that can, in turn, be converted into a Pearson correlation. Anyway, with two group means and ...
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1 vote
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### Can a Friedman's ANOVA be used for groups of different size?

The independent variable in my data is verb class: I have got four verb classes, each consisting of ten verbs. The dependent variables are accuracy (either 0 - incorrect or 1 - correct), and reaction ...
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### Multiple one-way ANOVAs, or are there better ways?

I analyze peptide content by mass spectrometry. I do 6 injections (replicates) for 4 experimental conditions (factor), and measure signal intensity (response). Usually, I would use a one-way ANOVA. ...
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1 vote
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### What is correct test to investigate difference between two conditions with repeated measures per subject?

I am having trouble deciding what statistical test I should use for my data. I have 5 subjects who rated attractiveness of 20 objects and 20 sounds of the objects on a scale of 1-5. I would like to ...
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1 vote
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### How to interpret two-way anova results?

Currently working on my thesis about the effect of the combination of FA and CCR on the strength of soil. The p-values from the two-way ANOVA for the two main factors and their interaction are ...
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### Post-hoc tests for repeated measures ANOVA with aligned rank transformed(ART) data

I'm working on a 2x3 factorial design with two within-subject variables and I'd like to test for both main and interaction effects. Since the data is not normally distributed, I've performed an ...
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### Dunnett's test for comparisons with Control - how to conduct ANOVA for 2 factors, as well as adjusting for different experimental designs?

From what I understand, before we conduct Dunnett's test for comparisons of treatments to a Control, we have to do ANOVA. However, for a 2-factor experiment, there seem to be a lot of problems to me. ...
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### Is a two way anova appropriate here?

Hello I am currently working on our undergrad thesis about the effect of the combination of FA and CCR to the strength of soil. We have 3 concentrations for FA and 3 for CCR, this is still excluding ...
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### Using ANOVA for model comparison with a different ratio, how does it differ?

When we compare two models with ANOVA then we typically compute an F-score like $$F = \frac{\left(\frac{RSS_1-RSS_2}{p_2-p_1}\right)}{\left(\frac{RSS_2}{n-p_2}\right)}$$ where subscripts refer to the ...
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### Making 3 comparisons with a ternary variable

I have a study in which I want to study the effect of a ternary variable $x$ in interaction with a binary variable $y$. The ternary variable is categorical, and for some reasons, I want to do the $3$ ...
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### One way ANOVA on compliance rates (by time period) with different lengths

I'm stumped a little on this, as in my stats classes we had very nicely packaged data with nice, normal data that was easy to understand! Apologies if this seems totally obvious. My data is a series ...
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### confirmation using the right tests

Users were asked to pick the AGE GROUP, GENDER and EDUCATIONAL LEVEL each from 3 provided options. I want to check the connection between each of these variables and answers to the question where user ...
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### ANOVA Type III understanding

I stumbled across something very interesting to me earlier, in the question and answer here: ANOVA type III strange results I reiterate the warning I found in the function documentation, highlighting ...
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### Multiple Linear Regression/ANOVA Help in Excel

I am working on a linear regression model and keep getting zero as my coefficients and the NUM! error as my p-value. I was told to organize the data this way but was then told by someone else that I ...
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### Is it better to perform multiple paired t-test or One-Way ANOVA test

I have 7 patients with blood measurements from two different tissues and at two different oxygenation states. We first took measurements from tissue A and B (Normoxia) and then we administrated oxygen ...
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### Which is the right statistical test to do (repeated measure - multiple subjects)?

Objective: To evaluate the effect of a training intervention on the performance of 6 independent subjects over 8 sessions. Study Design: Subjects: 6 independent subjects. Sessions: Each subject ...
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### Repeated measures ANOVA

I would like to seek help with a statistical analysis. I am conducting a study on the learning outcomes of different teaching methods. My dataset includes student IDs, binary data on exam performance (...
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1 vote
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### Different p value from Wilcoxon and ANOVA

I got a different $p$-value from a Wilcoxon test and an ANOVA test. When I use the Wilcoxon test, the $p$-value is less than $0.05$: ...
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### How to report ANOVA results when comparing to negative binomial models?

I want to report the results of an ANOVA test used to compare two negative binomial models in R: anova(model1, model2, test = "Chi") I receive the ...
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### Ancova or other test?

I am struggling to select the correct type of test for my data and would like to eventually run it in R. The design is as follows: A treatment vs control group of plants From each plant the following ...
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### Which type of ANOVA is the right choice?

I have a data set as follows and I'm wondering how: (i) this should be organised for an ANOVA test and (ii) which ANOVA (two-way mixed, two-way repeated measures) test is the correct one. ...
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### When is Tukey post hoc test result identical to Games Howell post hoc test for Welch ANOVA?

In what situations is the Tukey post hoc test identical to the Games Howell post hoc test? I have an ANOVA analysis where HOV is violated and I have a statistically significant Welch ANOVA result. I ...
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### Factorial ANOVA with composite dependent variable and interaction

I ran an experiment where participants were randomly assigned to a control or treatment condition and in both conditions each participant was presented consecutively with three pairs of products where ...
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1 vote
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### Repeated Measures Analysis of Variance Question

I have the following data set. ...
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### Analysis of Variance Assumption Testing When Multiple Error Terms Are Used

I am conducting a repeated-measures analysis in R, where blocks were sampled repeatedly over a season. ...
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### What is the difference between using logistf and brglm2 when dealing with complete separation in a logistic regression?

I am trying to looking at how the three factors A (5 levels, a-e), B (2 levels, a and b) and C (2 levels, a and b) affect the likelihood of event Y (1 = occured, 0 = did not occur). I initially ran a ...
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### Two Way Anova with Heteroscedasticity

I'm trying to run a two way anova test but the homoscedasticity condition is not met. My analysis is not balanced and I have over 3000 observations in my sample. Is it okay to proceed even if the ...
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### G*Power Mixed two-way ANOVA power analysis - sample size seems too small? [duplicate]

I am running my first-ever power analysis and I am worried that I am misunderstanding something about G*Power. I am running a 2x2 mixed ANOVA. I chose the 'ANOVA: Repeated measures, within-between ...
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### Explain ANCOVA to a newbie

I'm currently doing a statistical analysis between the effect of diversity and population density on depression in different counties across the US. I have currently run a two way ANOVA test and I ...
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### Non-Parametric Two Way Within-Subjects ANOVA

I have a dataset with 4 individuals that are measured twice in each of the 5 groups (so in total 40 observations). Subject ID Group Value 1 1 A 45 1 2 A 62 1 1 B 70 1 2 B 37 ... ... ... ... 4 2 ...
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### Anova not significant but post hoc is - how to interpret?

I have some data on animals, their diet (carnivore, omnivore, herbivore) and the angle of their orbits relative to the skull midline. Typically carnivores have more front facing eyes, whereas ...
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### Factorial anova results differ in R and SPSS

I am trying to run factorial anova in both SPSS and R but got different results. I convered the iv's into factors too. Any suggestions? ...
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### How to compare three groups of patients if one group is normally distributed but the other two are not?

Retrospective study involving three groups of patients. Group 1 are patient's diagnosed with sepsis. Group 2 are patient's diagnosed with a localized infection. Group 3 are "healthy" ...
1 vote
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### ANOVA alternatives

Imagine the follwing study: Objective: Test if a treatment enhances cognitive function. Groups: 29 subjects in intervention group, 20 in control group. Test: Answer as many questions as possible in 3 ...
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### APIM and ANOVA mixed?

I am proposing a research project that will include dyadic data in regards to couple satisfaction. It is a randomized controlled trial looking to investigate the efficacy of an intervention on ...
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### Sample size for REPEATED MEASURES ANOVA

I am calculating a required sample size for the Repeated Measures ANOVA (within subject). I came across two different packages and the results are different. Using "WebPower" package and the ...
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### Underlying model ANOVA and Kruskal-Wallis

Is the underlying model for one way ANOVA ($Y_{ij}= u + t_i + E_{ij}$) the exact same for Kruskal-Wallis test since KW is the non-parametric anova equivalent or does it have a different model?
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### Significant results from ANOVA post-hoc Tukey's, insignificant with welch-ANOVA post-hoc Dunnett's T3

I performed one-way ANOVA tests with post-hoc Tukey's to look at multiple comparisons and got highly significant results, but noticed the $F$-value on the ANOVA was high. The SDs in the groups were ...
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### Intuition behind Welch's ANOVA

I run some simulations and naturally Welch's ANOVA for unequal variances is pretty good compared to classic ANOVA and it seems it has no downsides. However, I still lack understanding as to why it ...
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### Help interpret these P-values [duplicate]

What does it mean when the model P-value comes out larger than alpha but the P-value for one of the main effects comes out smaller than alpha? The actual ANOVA is below. Alpha is 0,0027.
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### statsmodels.stats.multitest.multipletests: 1.0 pvalues [duplicate]

I am running a series of statistical tests between many lists of values all sampled from the same population. After computing pvalues, I thought to apply an adjustment with statsmodels.stats.multitest....
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### In a 2 arm pre-post RCT, is an interaction test on an ANOVA the same as a t-test of the change scores?

Say you have a 2-armed pre-test post-test control trial design. You want to test the effect of group allocation on the outcome variable. I simulated a version of this in R, using 3 different methods: ...
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### Group comparison with multiple group memberships

I want to statistically compare personality scores between different groups, but people can be in multiple groups. Is there anything problematic in just doing an ANOVA or a t-test since a respondent ...
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