# 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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### How should I analyze data that is paired and also repeatedly measured?

I have data collected from the same subjects (n=10) over 11 days, with measurements taken under two conditions each day: immediately after training(D0) and 30 minutes after training(D30). The data is ...
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### Is a correction for sphericity violation needed for post-hoc comparisons following repeated-measures ANOVA?

In a repeated-measures ANOVA, there is an assumption of sphericity, so that the variance of differences between groups is similar for all pairs of groups. A violation of this assumption can be ...
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### A Priori Sample Size Needed for Linear Mixed Model

I'm new to the site so I apologize if I fail to follow some norms. I am an early-stage doc student and am still early in my stats courses. In a class, I want to propose the following experiment based ...
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### multiplicity-adjustment w/ unequal variance & pre-planned vs post hoc

The (only) answer to this question says If the variability of the data in each category of your factor is non-constant, that would invalidate ... your multiplicity-adjusted post-hoc p-values. Why ...
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### Relationship between f test and t -test [duplicate]

I am working on a problem where I should derive the t test statistic from an f test given an ANOVA table (below). From my understanding, when we conduct an f-test we are using the variance to ...
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### How do I calculate the power and effect size for the Wald-type statistic of the RM-function from the MANOVA.RM package in R?

I have calculated the RM-function from the MANOVA.RM package in R and now need to calculate the statistical power of the test and the effect size for its Wald-type-statistic, including the ...
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### Understanding how ANOVA works

Consider a one-way ANOVA consisting of two treatments 1 and 2 (argument easily extendable to multiple groups). The sum of squares within groups (SSE) is defined as $\sum\sum(X-\overline{X}_{j})^{2}$ ...
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### selecting the most appropriate statistical test for comparison of multiple independent variables belonging to two groups

I want to compare the drinking water chemistry of two areas. A disease is prevalent in one area while the other area is almost free from this disease. I have measured the concentrations of 10 ...
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### Statistical approach to explain variance in different types of soil health data (organic material decomp vs lab based measures)

Seeking feedback and guidance on the statistical approach to explain variance in soil health data for a scientific paper on the sensitivity of organic material (teabag) decomposition to commonly used ...
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### How can I test if lower values on my regression line come from a level of a grouping variable?

If I have continuous x and y variables I can fit a simple regression. But I want to know how can I test if the lower and upper values of my variables are associated with different groups as in the ...
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### Appropriate way to correct for multiple hypotheses with multiple one-way ANOVAs and Tukey's post-hoc

I have a dataset with four groups and 14 different dependent variables. Based on the answer given here, I think the best approach for my analytical question is to perform multiple one-way ANOVAs, ...
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### Non-parametric ANCOVA post hoc test

I am doing a non-parametric ANCOVA (my residuals are not normally distributed and transformation did not help), I have been using the sm.ancova function from the sm package in R. Now I want to do a ...
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### Does a 2x2 study mean there are 4 groups or 2?

My study is a 2x2 design. There are 2 IVs: IV1 = sex (m/f) ; IV2 = control / experimental groups. Does this mean that I have 2 groups, and will therefore be using an independent T-Test, or i have 4 ...
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### Is there a statistical test where you test whether any of multiple separate analyses of variances or chi-square tests are statistically significant?

Is there a statistical test where you test whether any of multiple separate analyses of variances or chi-square tests are statistically significant?
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### Compairing two groups with paired data

I have two groups of samples: healthy and diseased groups. Each had an X treatment. So, I have a healthy baseline and healthy X treatment. The same for the disease group. Which is the best way to ...
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### Why does removing the offset change the F-statistic of an anova model in R?

When a linear model with only a single categorical variables is defined without an offset, the F-statistic reported by summary() and ...
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### Is repeated measures ANOVA suit my method

I use a randomized, double-blind, placebo-controlled crossover method. Participants visit 4 times. 1 time for placebo at sea level, 1 time for placebo at hypoxia room, 1 time for beetroot at sea level,...
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### plotting log-transformed data, but running statistics on raw data?

I intend to compare differences between means of eight groups. The differences between some of the means are only visible when I plot (in a box plot) the log-transformed data. However, I am unsure as ...
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### Formulas for type I, II, and III SS in R's car::Anova()

In the Anova() function of the car package one can specify whether the ANOVA should use type I, II, or III sum of squares to ...
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### How to do ANOVA/post-hoc analysis when 'control' is used to normalise the data?

I am analysing the transportation rate for a number of different mutants in a particular transportation system. I want to know how I can perform statistical tests on this data in a valid way, given ...
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### anova_lm function for a single multiple linear regression model [duplicate]

When using anova_lm from statsmodels with a single multiple linear regression model, how are statistics for each predictor calculated ? E.g. ...
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### What really happens if I run Tukey without running ANOVA first?

I see that the theory says that if I want to test for difference in mean between 3+ groups I should use ANOVA first, and if ANOVA rejects the null hypothesis then I might want to look into Tukey as a ...
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### Analyzing data with multiple treatment layers

I apologize if this is a silly question, but I'm having some trouble figuring out the best way to approach analyzing my data. I have a study where we investigated the effects of different dietary ...
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### Analyzing binary data with repeated measures across different levels in R

I have this data frame: https://i.stack.imgur.com/EGh1z.png It is the binary recorded responses (repeated measures) of subjects to 4 different tests under 2 environmental conditions (2x4 factorial ...
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