# 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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### repeated measure ANOVA of an experiment with several factors and conditions

3 cognitive factors were extracted from the performance of 10 subjects in an experiment. In this experiment, 6 different conditions were applied. Using repeated measure ANOVA, how can we find out ...
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### what do next when equal variances of a one-way ANOVA are not assumed?

I am running a one-way ANOVA and before looking at the results, the Levene test is significant. What should I do before looking/reporting at the results of my ANOVA and POST-HOC (Bonferroni). My data ...
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### 1 IV (3 categorical levels), 2 DV's (both scale data) - which test?

Terribly bad at stats - My grp sizes are horribly unequal and one is highly kurtotic - should I simply leave them this way or is there something I can do to 'normalise' while protecting effect size/...
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### ANOVA for multicollinear data? Partial Correlation?

I have experimental data. The data consists of simultaneous observations of some external variable $Y$ and multiple intrinsic variables $\vec{X}$. It is known that all $\vec{X}$ are strongly ...
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### What models does ANOVA compare, when a single model is provided?

According to the documentation of the R function anova(), it compares linear models with variables sequentially added. The following simple test shows, however, that this is not the case: ...
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### ANOVA and variables of importance [closed]

I need your help in the statistical methods to find the what factors are statistical different among three groups ( june-july-august). The average hospital length of stay(LOS) is about 5 in june, 9 in ...
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### Is a fixed or random model more conservative in running a two way ANOVA?

If for some reason (e.g., due to uncertainty or in error) I ran a 2 way ANOVA with one or both independent variables as fixed rather than random, or random when they are actually fixed, do I inflate ...
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### Chisq test for significance of intercept in R

I have a logistic mixed-effects model with both fixed and random effects. Imagine something like: ...
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### Is it valid to remove trials as outliers using IQR?

I have a repeated measures experiment where all participants completed several trials for each condition. My dependent variables are response time and accuracy. I am using the Interquartile Range as ...
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### Why does Tukey's "1 - slope rule" work for transformations in ANOVA?

I'm reading the book STAT2: Modeling with Regression and ANOVA. In Section 5.6, the authors consider what to do when you want to do a one-way ANOVA but the group standard deviations are not equal. ...
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### Two Between, One Within Repeated Measures ANOVA in R (aov) vs (anova_test)

I have the following dataset, of which this is a subset: ...
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### How to carry out a three way anova when assumptions are not met?

I have a data set of 543 participants with one dependent variable of a score and three independent variables of teacher age, student age, and teacher self-efficacy. When carrying out the tests for the ...
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### Can I use one-way ANOVA and any kind of correlation test for data with unequal sample sizes?

I have 4 different populations of chickens (one of them is my control group and 3 treated groups (their diets treated) ). I sample 16 individuals from each population. From each individual, I obtained ...
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### How to decide which variables to keep in logistic regression model based on anova(model, test = "Chisq") and glm output [duplicate]

I’m new to logistic regression and was hoping for some help in picking a "best fit model". Say I have a group of students who are assigned a job after college. Everyone can request their top ...
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### How do you test homogeneity of variances with weighted sample design?

I am working with a weighted sample design and I am trying to perform a one-way ANOVA, but I need to test for homogeneity of variance first through the Levene test. SAS offers the option to add ...
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### How to interpret anova(model, test = “Chisq”) for logistic regression model?

I’m new to logistic regression and was hoping for some help in picking a "best fit model". Say I have a group of students who are assigned a job after college. Everyone can request their top ...
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### Interpreting ANOVA results with significance within-groups but no significance between-groups

Hypothetically, what can be concluded if a WABA output shows within-group significance but lacks between-group significance? Would this imply that research should focus on the individual level of ...
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### Using an online tool to compare different groups without raw data

I have a question regarding using the https://statpages.info/anova1sm.html tool that has been mentioned here and there for comparing means in different groups. I am currently looking to compare my ...
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### Need help for statistical test selection

I am currently doing SPSS data analysis and I am not sure which statistical test to choose for my analysis. I am measuring the increment in the concentration of some chemical substance from 10 ...
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### Seeking an example of a nested ANOVA with unequal Ns

This is the design: Independent variables: Gender, Schools Dependent variable: A cognitive knowledge measure (K) Null hypothesis: Mean K for men = mean K for women I am interested in male-female ...
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### How to determine if one variable affects the relationship between two separate variables

I have a dataset where two continuous variables are almost perfectly correlated. There is a third categorical variable and I need to perform a statistical analysis to determine if the categorical ...
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### What sort of ANOVA do I have?

I'm trying to work out what sort of ANOVA would be applied. I just can't work my head around it so that I can report it. I am trying to work out the efficacy of CBT vs medication. There are two ...
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### Best way to compare two treatment groups to a control

I'm trying to compare two different fertilizer treatments to a control group (no fertilizer). I ran a model like this: ...
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### Appropriate Way to Measure the Influence

I have two online marketing channels A & B and have their sales data for the past 24 months, as below. Total sales (conversions) are measured as A+B. B is the cheaper channel and hence my ...
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### How to calculate Mean Squared Error when there are multiple observed y values for a single x value?

Given a data set where there exists multiple different observed y-values for a given x-value, how do I calculate Mean Squared Error? The formula implies that I subtract the predicted from a singular ...
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### Using the anova function in R with more than two models

My question is about the anova function from the stats package in R. The function produces unexpected results (at least ...
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### Which approach to analyse spatial data? Multiple t-tests, ANOVA with repeated measures, or something else?

I need to extend an existing analysis for which I do not have full information about their methodology. I have land surface temperature (LST) data for several utility-scale solar sites derived as ...
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### anova tukey posthoc writing up result

I am writing up Tukey posthoc result and comparing conditions A, B, C. The test shows that A and B are both significantly higher than C. However, how can I write that in one sentence? Originally, I ...
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### Suitable method for multi-condition bench test

Given the setting below, what is the preferred method to evaluate whether any two conditions out of a multitude of conditions differ significantly? Let's say I have an experiment with 10 samples where ...
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### ANOVA or T-test for multiple groups, each group with a set of observations?

Can someone please advise on which sort of experiment or test I should run for the following. I want to know which messages would potentially resonate more within a population. I have conducted ...
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### Mediation analysis in 2 x 2 experimental design

I am doing a bunch of experiments. In all of them, I have 2 independent continuous variables with 2 levels, And I have run 2x2 independent measures factorial ANOVA on them so far. However, in one ...
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### Why type III sum of squares is not recommended to use when there is significant interaction?

I did notice that in the following example, I obtained a insignificant main effect for treatment when including interaction, although the treatment is clearly effective. Any intuitive explanation? ...
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### Comparing Means of 2 Groups of Different Sizes Across Time

I am trying to figure out the correct test to compare two different groups between two-time points. I will have a baseline data collection of the stress levels of male and female caregivers and a ...
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### linear regression/ANOVA with a covariate measured on a different set of objects

CV has helped me many times but it's my first question as I am struggling to find the right type of analysis for my problem. I have a continuous response variable measured in several groups and my aim ...
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### R ezANOVA vs. R aov for 2-way RM ANOVA. Different degrees of freedom and p-values (consistent, but different)

I'm trying to reproduce the same analysis with ez::ezANOVA and aov. My design: DV: estimate IV between: Part (of something), 2 levels IV within: Timepoint, 2 points repeated per each subject ID no ...
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### Significance for raw and absoulte values in repeated measures

We are running repeated measures ANOVA with 2 independed and 1 depended variables. The goal of our study to examine precision in participant's estimations about depended variable. This depended ...
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### How do you interpret LASSO dummy coefficients?

Let's say I have the typical ANOVA where X has 3 categories and I one hot encode. I then have: Y = b1X1 + b2X2 + b3X3 b1, b2, and b3, are basically how much mean(Y | X) deviates from 0 (and if the ...
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### Analysis of Deviance in R returns a significant factor, but the mean of each group does not show any difference

We performed a 45s test with dogs and humans, we measured the distance between the dog and the human every 0.25seconds with GPS. The data for one subjects are in the following format: Subject_Id ...
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### Running a simple anova test in R (repeated measures)

We are studying 3 different proteins, each under 9 different conditions at 3 different timepoints (Day 1,2,3). For these we have 3 biological replicates. So we have 81 different experiments (3 ...
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### Proof on $SS_{AB} / \sigma^2 \sim \chi^2_{(I-1)(J-1)}$ under the null hypothesis $H_{AB}: \delta_{ij} = 0$ for $i=1,\dotsc,I$ and $j=1,\dotsc,J$

First time to ask a question. I am now reading a textbook "Mathematical Statistics and Data Analysis, 3ed" by Rice. On Page 495, there is a Theorem B for the two-way layout ANOVA. Let me ...
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### How do you interpret ANOVA with transformed response?

Let's say I have a quantitative variable Y that ranges between 0 and 1. I have a categorical variable X that has 3 levels, A, B, C. Since Y ranges between 0 and 1, I transform all of Y using the ...
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### Fixed and Random Effects / Fixed and Random Factors

What is the difference between a fixed effect and a random effect? Are fixed and random effects different from fixed and random factors?
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### How to calculate pooled variance when Block(replicates) exists?

Here is one data I generate by R ...
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### Need help analyzing data with multiple 'replicates'

I inherited a project, and I'm pretty lost on how to appropriately analyze the data. Here is our design: Two factors: One 'behavioural' with three levels (let's say: 'Sleep', 'No Sleep' and 'Short ...
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### Can I use LMEM to select categorical features if some features are interactions?

I have sort of a general best practices question here. I using LMEM to do some exploratory analysis from a project, and I just want to see whether my approach holds any water. The project is this -- I ...
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### Why is my BLUP not Best?

I want to verify, computationally, the bestness of the BLUP for predicting random effects. Let  Z=\begin{bmatrix} 1&0&0\\ 1&0&0\\ 1&0&0\\ 0&1&0\\ 0&1&0\\ 0&...
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### If the assumptions of ANOVA fail to reject at 99%, how can that be applied?

I think I am on the right track, but I would rather know. Initially, when the results of Levene's and Shapiro's were significant at 95%, I tested and investigated the data in various ways. I used ...
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### Finding variable contribution in manova

I have a dataset with one grouping factor and some dependent continuous variables. Given the difference, I want to know which variables contribute the most to the difference, like this variable A is ...