# 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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9 views

### When to use distance between distributions instead of using median based statistics?

I have a problem where I have to compare the effect of X ( univariate random variable) on distribution of Y (univariate random variable) between 2 different cases. Y is not following a Normal ...
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### Which test to use? Independent data or not?

What I have is a cross section of a bone divided in 60 equal slices. These 60 slices form 4 groups of 15 slices each corresponding to the 4 anatomical orientations (anterior, lateral, posterior and ...
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### Statistical tests for one independent variable and dependent variable without any levels

I am doing a research paper project on personality and social media. My research question is: Does having a certain Big Five personality trait predict how much time is spent on social media? Gender ...
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### anova() for Regression model comparision

I did a regression and want to compare my models to pick the good one. However, I got kind of warnings. I really don't understand what does it mean. The warnings are here ...
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### pureErrorAnova(alr3 package on R) would work for two-way factorial anova

I have a balanced 2x5 anova factorial which 4 replicates each group. I'm trying to check the Lack of fit and I came accross the pureErrorAnova - alr3 package (Im using R software). My independent ...
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### Difference between anova(car) and ezANOVA

I am trying to interpret results form two-way ANOVA on the data presented in the figure below. i implemented the ezANOVA following this explanation. However, when I use the anova function in the car ...
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### Should I use ANOVA or paired t-test?

For my statistical analysis, I want to find out: If there is a statistical significant difference in PM2.5 levels in 2019 and in 2020**. If there is a statistical significant difference in PM10 ...
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### Transforming multiple round count data into single percentage score per participant

I am planning a 2x2 between-subject experiment with n=25 participants per cell and n=100 participants in total. every participant will only be in each treatment once. The participants will play 10 ...
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### Why don't we consider pre-test scores when using one way ANOVA?

Newbie here. I'm trying to determine whether there are any statistically significant differences between the means of four independent groups as follows: ...
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### Chi-square or ANOVA for two groups with multiple possible categories

I am working on a research project examining diagnoses in two populations, lets say A and B. Then I categorize their diagnoses: D1, D2, D3, ... (about 9 of them). (N>500 for both groups). So D1 is the ...
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### 2x2 design - two separate hypotheses and one interaction hypothesis. how many tests?

I am planning to conduct a study with three hypotheses in a 2x2 between subjects design. Both independent variables are categorical and the dependent variable is metric. Let's say the levels of my ...
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### What core topics would all statisticians be required to know?

I would like to know what topics are considered 'core knowledge' for a statistician. Please keep in mind I know very little about statistics. At my university, I hear statistics students discuss ...
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### Plotting confidence interval - graph showing odd results

Just wondering if anyone can help me analyse the following: I plotted my confidence intervals from a GLM, and found that a lot of the points don't overlap the C.I. What exactly does this mean ...
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### Normal distribution assumptions in ANOVA vs. Linear Regression

I don't get it. I am planning to conduct a 2x2 between-subjects measurement with a sample size of 30 per cell, hence four groups that I want to test for the difference. Is there a difference in the ...
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### Selecting Appropriate Analyses for Time-Series Data in R

I'm working on an analysis of leaf litter decomposition, which was done with two separate microcosm experiments. Example dataset: ...
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### Stuck on confidence interval analysis for GLM

I'm really new to R, and sort of stats in general. I've been using a GLM to analyse a series of data, which is basically tracking how concentrations of DNA change over time, when different treatments ...
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### What statistics can compare dataset with shared values from same data source?

Note- The following question was first posted on Math Stackexchange and I was advised in the comments to post on the Stats Stackexchange. Please forgive me if reposting in this way is considered ...
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### Perform ANOVA on imbalanced Data in Python

Is there a way I can perform ANOVA [or any statistical test] for the following research problem. I have a variable Plant Survives (1/0) and another variable Amount of Hydrogen( Continous). I want to ...
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### Confusing results of pairwise t-test

I wanted to compare the means of 3 communities based on heights.I have a hundred samples for each community. I checked if the communities are normally distributed with Shapiro-Wilkis test first and ...
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### How can I compare the means of two continuous data sets against a categorical variable? [closed]

I have a category that is Yes/No Example: Patient 1-10 are "yes" to smoking. I want to compare the mean velocity of running versus biking for patients 1-10 Patients 11-20 are "no" to smoking I want ...
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### ANOVA blocking for multiple parameters

I'm trying to learn ANOVA and see how it applies to a certain experiment. In the experiment we are trying to predict if a certain brain signal is predictive of whether a mouse would do the correct or ...
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### Testing for equality of variance for more than 2 groups

How do you test for equality of variance between, say, 3 groups? Is there an extension of the two-sample F-test? Or is it OK to just run multiple F-tests or permutation tests among 3 groups?
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### Repeated measures ANOVA for equality of two measure

I have used two different designs for a questionnaire to measure the same variable, and I want to investigate if changing the design led to a different measurement as a result. I have a within-...
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### Statements about variance ratios without Anova

I have a dataset with the weight variation of parts and the absolute assay of a certain content in those parts. However the data of the weight and assay was not taken from exactly the same parts. Now ...
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### Correct group definition and ANOVA test application

I have a dataset with multiple (n=140) repeats of simulations run under the same conditions, however, there is a source of variability in the model. I would like to ...
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### R: Mixed ANOVA works with the aov{stats} function and fails with the anova_test{rstatix} function. Why?

I can implement a rather complicated mixed ANOVA in R with the aov{stats} or the lmer{lme4} functions, but not with the anova_test{rstatix} nor the Anova{car} functions. My question follows: How can I ...
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### How to access to members of a test result in R [migrated]

I am conducting the Levene's test as well as Shapiro-Wilk test on a large set of data. I am wondering how do I access to particular parts of a result and store them in a CSV file to simplify reporting ...
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### One-Way Repeated Measures ANOVA & Simple Linear Regression SPSS - understanding Independent Variable

Research Question: A researcher wants to investigate the emotional experience of discrete emotion categories in children aged 7-11 (50 participants in total). To assess subjective emotional experience,...
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### Incomplete block design

I have data among several variables sampled from deep-sea sites located in a marine canyon. In total 13 sites (n=3/site) were sampled. Sampling was conducted on 5 sites along 1 transect (~ 500 - 2200 ...
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### Cohens d effect size calculations across 3 groups

Is it possible to calculate a single Cohens d effect size, across 3 groups? I have successfully used Cohens d to calculate the effect sizes between state 1 and 2 (as simple example given below) for ...
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### Applying ANOVAs to overlapping data subsets

Assume I have an experimental design involving two factors, each of which has three levels: Factor 1: level 1 level 2 level 3 Factor 2: level a level b level c However, during the experiment I ...
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### Mallows' C MSE bias and sampling error component

If a true quadratic regression function is E(Y) = 15+20X+3X^2, and the fitted linear regression function is Y_hat=13+40X, for which E(b_0) = 10 and E(b_1) = 45. What are the bias and sampling error ...
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### Can I use a GLM to measure changes over time? (R help)

I'm running an experiment in which I'm measuring the changes in DNA concentration over time (response variable), and my predictor variable is temperature. I have three different experiments, with ...
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### Interpretation of directedness in ANOVA

As far as I know, ANOVA results can be interpreted with respect to mean differences between 2 or more groups. But, we can not make any inference on which mean is larger or smaller in a statistically ...
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### mixed model with repeated measures in R

I have a crossed design with 2 levels of Trt1 fully crossed with 5 levels of Trt2. This same design is applied at 10 different locations. Now the samples are collected from the same subjects at 6 ...
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### Hypothesis Testing with ANOVA tables

I need to test the hypothesis that the amount of rainfall doesn't affect the yield of a crop. Other predictor variables in the model I have to use are the variety of crop and the soil that the crop is ...
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### $\mathbb{G}=(1,B,T,B \times T)$ is an orthogonal design

I have an orthogonal system with 2 factors, B and T. I know that B and T are orthogonal geometric. But I also need to show that that the system $\mathbb{G}=(1,B,T,B \times T)$ is an orthogonal ...
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### Friedman test when the observations are different from each other

I have database which has data about 72 plants, that got 6 different treatments. I have measured the weight of those plants every day and every hour for the past two weeks.so basically there is ...
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### Why I am getting different coefficients for R's classification model?

Dataset Consider the following dataset which measures the price of a computer given different configurations Situation After applying the four-way classification model as below, we have the ...
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### Likert scale questionnaires with ANOVA and Kruskal-Wallis test

Could someone recommend me sources where I could find illustrated examples, solved by hand and/or using software, on how a Likert scale questionnaire (with more than 1 question, say 10, 20, etc. ...
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### Pairwise ANOVA test if I have data about 6 separate groups

So, I have a data about 6 groups. And I made an ANOVA test in R, it gave me F value of 15.34 and a small p value. What could indicate that I should make a pairwise ANOVA test between two of these ...
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### Why is there such a discrepancy between the sum of squares I computed and R computed?

Dataset The data is a typical dataset encounted in two-way classification model: Situation I applied two-way anova by running R on this dataset to look at the sum of squares ...
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### Different results for model comparison using ANOVA function for REML and ML

I got this interesting results when I use anova test to compare two nested models. I fitted two nested mixed effects models with ...
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### Why the variable type is discrete ordinal and not interval?

Assume that we have a 5-likert scale questionnaire, we want to measure cheating behavior (plagiarism, use of crib notes, etc.) among students. We have 0-disagree and 1-agree. So I’m assuming 0.25-...
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### Repeated Measures ANOVA or MANOVA

I am studying the effects on an intervention on one group of individuals two times, before and after intervention. I am measuring social skills using a rating scale. The rating scale has an overall ...
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### Significant effect with overlapping boxplots?

I'm puzzled about some of the results that I got, after plotting the data. I have a dataset where 38 participants are tested on three conditions "time" and are thus tested three times. I figured this ...
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### Dunnett post hoc test significance

I compared the effect of different concentrations of antibiotics with the anova. As I am only interested in which concentration is significantly different compared to the control I performed a post-...
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### Analyzing Likert scale data

I am doing an university project, and a big part of my data is ordinal (Likert scale). In some of the hypothesis I have Likert scales both as DV and IV, so for example IV is I shop on a tight budget (...