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Questions tagged [levenes-test]

Statistical test used to assess whether the variance differs across a number of groups. This test is sometimes used to justify the assumption of homogeneity of variance when using ANOVA or $t$-tests.

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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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Variance ratio below 3

Can it be assumed that the repeated measures (RM) ANOVA is robust, even after having a significant Levene test for a variable? What about if the ratio between the maximum and minimum variance is below ...
mdscience's user avatar
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Calculate Levene test in R

I'm trying to calculate the Levene tests with multiple interactions. ...
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Heteroscedasticity in linear mixed effects models (lmer)

I am computing the following model in R, using lme4::lmer: m3 = lmer(e ~ (X*Y*Z) + (1|ID/R), data = data_transform) e is a continuous variable. X, Y, and Z are ...
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How to analyze variance from repeating a test with the same unit vs variance across units?

Suppose I want to buy a CNC machine to automate guitar-making, for instance. I have access to a warehouse of CNC machines that are all reported to be the same model and advertised as having equal ...
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Which Levene statistic do I report?

I am writing a paper comparing quantitative values across $5$ groups. I have performed an ANOVA in SPSS 29 and have requested from the software the Levene statistic to judge if there is homogeneity in ...
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Can the Levene test be used to explicity test variance inequality instead of equality?

The Levene test is a statistical test that can be used to test the equality of variance between two samples. I have two paired samples (N = 751 per sample) that clearly have a very different variance, ...
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Statistically comparing the variance of two dependent samples

I have two dependent samples of data. Each sample contains N = 800 values (data points) and stem from the same human subjects, that is, sample one is the pre-experimental and sample two the post-...
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How to check for homoscedasticity in a mixed effect model with longitudinal data in r

I am new to using mixed effect models and all the information online has me quite confused. I hope someone can help me. I have data of patients who did the same test at three different timepoints. I ...
Anandi Nobel's user avatar
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RM-ANOVA vs Mixed Model

I am trying to find the best analysis approach for my data. Simply put, I am looking at a treatment for the impacts of drug exposure before birth. My groups are: 1 - no drug, no treatment 2 - drug, no ...
izzy's user avatar
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Advice on Strategy for Evaluating Significance of Difference Between Two Variances

I have a dataset of ~800 observations. The observations are tracked according to two variables: a year and a value. The years are all between 1980 and today. I've divided the observations into two ...
oneyellowlion's user avatar
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How to interpret results from the data if Levene's test is violated?

I'm doing ANCOVA analysis. So, the assumption of Levene's test is violated which means I have to run a non-parametric test. Does that mean I can't interpret other results that I obtained from the data ...
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Assessing homogeneity of variances assumption for numeric variables

I'm fitting a model with a 2-level categorical and a numerical predictor. As far as I'm concerned, I cannot use car::LeveneTest() to assess homoscedasticity since I ...
Larissa Cury's user avatar
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Why is there an apparently large difference between Bartlett and Levene's test in this problem?

When running tests for homoscedasticity, using R gave the following results: ...
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1 answer
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Levene's Test and residuals vs. fitted plot lead to different interpretations about heteroscedasticity

I am performing a one-way ANOVA in R with the following data: Cu Day CC Cu1 49 30934500 Cu1 49 26860125 Cu1 49 46524750 Cu10 49 15272561 Cu10 49 31601659 Cu10 49 17627634 Cu100 49 3718127 ...
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Two-Way anova assumptions not fulfilled

My task is to determine whether two different categorical variables (residence location (city/rural) & residence size (small/medium/large)) have a connection on one numeric variable (residence ...
Niko Vyyryläinen's user avatar
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Feature Importance with categorical independent variables and non-normal continuous dependent variable

I want to study the feature importance of a model with a continuous not normally distributed variable as response and a set of categorical and ordinal independent variables, with unequal variances in ...
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GLMER levene's test significant

I am running a glmer and I checked for assumptions of normality (plotting QQ plots) and homogeneity of variances using Levene's test. My variable A is something ...
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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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Which variance test is needed?

I have the following data A= c(45, 55, 46, 67, 23) B= c(34, 54, 29, 66, 58) C= c(56, 76, 60, 37, 55) I want to know if there is a significant difference between the variance of A, B and C, which test ...
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What statistical tests or procedures should I conduct for analyzing a repeated measures design experiment?

I have conducted a repeated measures design experiment on Paivio 1971's dual coding experiment, but my two conditions are Dual-Coding (visual + auditory) and Auditory on Animal Sounds. There are two ...
Arvin Azodi's user avatar
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R function for weighted two-sample t-test **with Welch-adjusted t statistic**?

I'm conducting a hypothesis test for the difference between two groups. The file dat1 contains all observations of measure for ...
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1 answer
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Good variance test when the distributions have different shapes but I really want to test the variance

Consider $X\sim N(1,1)$ and $Y\sim exp(1)$. The distributions are totally different, but they do have equal variance, so if I were to sample from these and test for unequal variance, I would not want ...
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testing for significant differences in variance while controlling for a covariate

[first question, apologies any ambiguities/violations of question conventions] Within a dataset, I have a continuous variable of interest (X), and I want to test for differences in variance of that ...
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1 answer
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How to do a levene's test without a grouping variable?

I have a list of people who did a test before and after an intervention. And I want to compare their pre- and post-scores. Now before I do t-tests, I have to check for heteroscedasticity with a levene ...
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Levene's Test in two different samples [closed]

How can I perform in R, a Levene's Test of two different samples to check homoscedasticity without being none of them a factor and not building new variables (what I really want to do is to compare ...
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0 answers
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Repeated measures test of (un)equal variance

I have a repeated measures design with two groups and two measurements of a value $x$ (the minimum signal level needed for reliable detection). I measured $x$ with procedure A and procedure B. One ...
StrongBad's user avatar
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3 votes
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Test for non-normal data with homogeneity of variance

I'm new to the platform and would like the following question to be answered: I have performed a latent class cluster analysis with 28 variables and 9000 observations, for which I am currently ...
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1 answer
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Equal Variance Assumption- Levene's Test with different sample size

Between-subject & repeated measures experiment & with two groups: Treatment and control. I have 15 in treatment and 20 in control. Can I use Levene's Test with an unequal sample size? ...
mashedpoteto's user avatar
1 vote
1 answer
331 views

Stratify the analysis if Levene's test fails

I have a question about the correctness of a statistical analysis. I have a variable called L, which is the log of the number of bacteria present in some foods. L is a function of the treatment T (...
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Test of variance between 2 treatments split in multiple groups

I want to compare the "spread" of the data points in two treatments (blue and green below), so I went for a Levene's test of variance equality. However, my data consists in 12 subgroups ('X' axis in ...
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Is it okay if one of the residuals in a repeated measures ANOVA fails in Shapiro-Wilk test for normality

I am currently running a Shapiro-Wilk test on the residuals of a repeated ANOVA model. The repeated-measures ANOVA was conducted to measure two main effects A & B. The ANOVA summary is listed ...
Rudresha Parameshappa's user avatar
2 votes
1 answer
156 views

What test to use to determine whether a binary variable is distributed differently among groups

I have a set of data which has been grouped into 5 clusters. What I would like to do is, for each variable, determine whether it's distributed differently across the clusters with respect to the ...
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1 vote
2 answers
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Levene's test with a two-way anova

I am trying to perform a levenetest on my two-way anova. leveneTest(Score ~ Party + Group, data = Data) But R just screams at me saying ...
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2 votes
1 answer
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Does it make sense to do Levene's test in relation to ANCOVA?

In relation to another question, Ben Bolker writes that if you have all-categorical predictors, you can test for heteroscedasticity (and other issues such as non-Normality) by dividing the ...
user1205901 - Слава Україні's user avatar
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Modeling interaction in variance

I run an experiment on both men and women participants, where I manipulate an independent variable. I know that the manipulation causes greater variance in the outcomes of the experimental group (a ...
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299 views

Ancova for unequal variances [duplicate]

What is the best way to compare two non-homogeinous populations (Levene's) with covariates (e.g. age). I know ancova assumes homogeneity. Is there a way around this? Many thanks
hH1sG0n3's user avatar
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1 answer
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How to deal with unequal variances in repeated measures ANOVA

Angry Birds is a video game in which you fire birds at pigs. A (fabricated) study was set up in which people played Angry Birds and a control game (Tetris) over a two-year period (one year per game). ...
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Appropriate method to assess scatter or variation in groups with dramatically different means

I am working on a product fabrication process, and I want to demonstrate the consistency of my product. To do this, I am trying to measure the variation in the extent to which a biological material is ...
user219200's user avatar
5 votes
1 answer
114 views

Use of supportive inferential statistics (e.g. Levene's and normality tests) in underpowered samples

We know that underpowered statistics greatly increase the probability of a type II error (by definition), meaning a greater chance of failing to reject the null hypothesis despite the existence of a '...
Josh Blake's user avatar
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42 views

Ruling out collusion in peer evaluation

In my class I have groups of students making presentations and the rest of the class evaluates them. Since their scores are curved the students do have an incentive to collude and mark other teams ...
K R's user avatar
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8 votes
1 answer
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Comparison of variance between two samples with unequal sample size

The primary goal of my analysis is to compare the variability in the response variable, Blood Pressure, between sample1 and sample2. The secondary goal is to test for a difference in means. I do not ...
Erika_Hammerl246's user avatar
7 votes
3 answers
9k views

Non-parametric alternative to simple t-test

I have five numeric variables of two populations (each of them with 60 individuals) and for each of those five variables I want to know if there is difference in the means. I was trying to use a ...
Germán Ruelas's user avatar
1 vote
0 answers
4k views

Interpreting new Levene Statistic shown by SPSS

I want to perform a between-subjects one way ANOVA on my Data. I have 4 experimental groups. I performed the tests of normality and homogeneity of variances. The output from SPSS for homogeneity of ...
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Performing a two-way ANOVA, I get a non significant Levene's and a significant interaction effect. What it the next step?

In the case described above, our Professor instructs as to interpret the simple effects by using MSwithin of the two-way ANOVA. In case the Levene's test is significant though, he instructs us to ...
D. Kalli's user avatar
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Statistical tests, when data are not normally distributed & variance is not equal

I have a data with two variables - one variable is quantitative, and one is nominal (4 categories). I ran the normality tests and it turned out that this quantitative variable is not normally ...
Mary's user avatar
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6 votes
1 answer
781 views

Levene's test assumptions

Does the Levene's test have any assumptions? If so, what are they? To my surprise, neither my textbooks or Wikipedia, mention any assumptions for this test. But I seriously doubt that the test doesn'...
user1561358's user avatar
6 votes
1 answer
4k views

Smallest possible sample size per group in Levene's test

Recently learned that Levene's test is a one-way equal-variance ANOVA done on absolute values of residuals calculated from the mean within each group. For one-way ANOVA the minimal sample size seems ...
Karolis Koncevičius's user avatar
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0 answers
2k views

Levene test in R

I tested for equality of variance between two groups in R ...
chrisuw92's user avatar
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0 answers
266 views

Testing equality of variances in panel data

I am familiar with Levene's test (Wikipedia link) for equality of variances, which is robust to non-normality, but assumes observations are independent. Today I was wondering what to do when you want ...
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