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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What Adjustment shall i choose if Levene Statistics is Significant

I am using BlueSky Statistics. My Levene Test for Variance is significant. What test shall i choose. All test that the software shows are for insignificant variable like Bonferroni, Tukey, or Holm. ...
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1) Testing for homogeneity within a group and 2) testing if factors affect outcome

I am a research intern at a plant breeding company and do not have much SPSS experience and would like some advice considering this question/research. The added image visualizes steps 1 to 4; see ...
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ANOVA curve representation

I am researching the embodied cognitive intent exhibited by archeological assemblage, e.g., in ancient glass. I work out homogeneity by ANOVA so as to suggest a Levene's value. For both the real ...
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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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What is the reason for using Fligner-Killeen test on non-normal data, if ANOVA requires more or less normality? What are the other applications of it?

Variance homogeneity tests like Bartlett or Levene assume approximate normality of the data among groups. That makes a lot of sense, if we the tests before running ANOVA, which wants the normality as ...
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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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Box's M Significant and One variable in Leven's test failed for quality of variance SPSS

I am doing a MANOVA test as part of a psycology project and have to use MANOVA Box's M gives a sign value of less than 0.05 (stated to be used on imb's website) but greater than 0.001 (stated to be ...
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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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Homoscedascity tests for Two-Way ANOVA (a factor and a covariate or two factors)

I have the following formula: glm1 <- glm(y ~ g1 + g2, data = fish, family = binomial) y is a binomial variable: num 1 1 0 0 1 0 0 0 0 1 ... #There is (1) or ...
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Why is the Brown-Forsythe test the only test returning: “The group variable must be one factor”?

When trying to run the bf.test, I get the error below. The group variable "Group" is a factor and ranges from 1 to 3. I've tried it with and without as.data.frame()...
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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 ...
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Testing for differences in water temperature variability of three sites

I believe this should be a very easy problem to solve but I can't seem to resolve this myself. I have water temperature data of three sites. Temperature was logged every 30 min for ca. 2 years. I am ...
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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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133 views

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? ...
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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 ...
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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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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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789 views

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 ...
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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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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
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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 ...
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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 '...
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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 ...
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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 ...
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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 ...
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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 ...
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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 ...
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414 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'...
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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 ...
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Levene test in R

I tested for equality of variance between two groups in R ...
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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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One-sided test of equal variances with small (but equal) sample size and non-normal data

I have two groups, each with 6 observations. One group was generated by an old test method. The other group was generated by a new test method. I would like to test if the new method produces more ...
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Test for homogenity of variances, Levene's test and fligner-kileen yield different results

I have two sets of data, in which the first dataset contains 3346 values and the second dataset contains 1168 values. The variance of the first one is 13.88% and variance of the second one 13.96% The ...
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ANOVA one way: Levene test is significant. Welch and Brown Forsythe Test are the solution?

I trying to run a one-way ANOVA to compare 3 groups (Northern, Center and Southern regions) but Levene test is significant. Kurtosis and Skewness are ok but the equal variances assumption is violated. ...
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990 views

How to rectify Heteroskedasticity/Failed Levene Test in Linear Mixed Models?

I am newer to mixed models and ran into a confusing spot with one of my models because it violated the assumption of homogeneity of variance. I am running this in R and using lmer from lme4. Sample ...
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Normality of distribution: Shapiro-Wilk and Levene tests

I have Likert-scale data from an experiment with 5 conditions, each of which has a different treatment and one is a control group. The goal is to compare the effect of the treatment between the ...
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What affects Levene's-Test Sig. value?

I did a Standard Error Plot of my two treatments, and homogeneity of variance appeared to be justified (there was only a slight difference in variance). However, then I ran Levene's during my ...
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What type of test should I use on my data?

I am testing gas mileage between three brands of gasoline. I am testing on a small population of 10 cars. Hypothesis: Cars using higher grade gasoline will have a significant higher gas mileage than ...
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Is it acceptable to do an unpaired t-test without Levene's test for equality of variance?

I collected data for my study to compare with the published norms of two other studies. All three groups are from different populations (based on occupation). I will be using a two-sample independent ...
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419 views

Mixed-ANOVA Design - Assumption

1) In a Mixed-ANOVA design, with one-between subjects (2 levels) and one within-subjects test (2 levels), do we normally check the Levene's output to ensure that we are not violating the assumption of ...
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Levene's Test on 2-by-2 Mixed Factor Anova

It is my understanding is that a Levene's test is simply looking at to see whether there are any differences between the differences of the mean. Here is some data: ...
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Assumptions on the Levene's test

I'm trying to conduct the Levene's test for 10 non-normal samples to study an eventual heteroscedasticity. I was trying to justify my applying of this test, but I can't find it's clear assumptions. ...
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Advice regarding statistical analysis - two way ANOVA for a data set with unequal variances?

I have a data set classifiable by gender (male and female) and genetic status (WT and mutant). The WT data is mostly consistent with tight standard deviations, whereas the mutant data is highly ...
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2x2 ANOVA with non-normal distribution and Levene failure

I am doing an MSc dissertation in psychology at the moment. I have collected data from 307 groups, and I am trying to run a 2x2 ANOVA. The DV is 'number of conversations'. One IV has 2 levels (yes or ...
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Differences between Breusch-Pagan test and Levene's test

I am trying to check homoscedasticity of Residuals to use an ANOVA in R with data with one variable and three groups. I have been checking options to do it, and I would like to know when to use a ...
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Test for equality of relative variation

So when I have two vectors of unequal sizes with different means and different standard deviations. One has coefficient of variation of 10% and the other 15%. Which statistical test would I use to ...