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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When running MANOVA and you have a significant Levene's Test prior to the univariate tests, what is the best course of action?

When running MANOVA, if Levene's test is significant, aka homogeneity of variance is violated, before the univariate output, aka the test of between-subjects effects, what is the best option after? I'...
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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 ...
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Is the Levene test parametric?

I have seen that the Levene test is described as parametric and nonparametric and I am wanting to know exactly which it is. I am referring to this test: https://www.itl.nist.gov/div898/handbook/eda/...
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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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21 views

What are the proper steps to perform an ANOVA in Statistica?

My friend and I are doing a project for our Statistics course. We have to do an ANOVA on this: Gender Technique Increase of Capacity Female T1 11,5543217 Female T1 60,6939505 Female T1 4,83982304 ...
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Levene's test quadratic vs absolute - Difference?

I am doing an anova in matlab and to check for homogeneity of residual variances I want to perform a Levene's test. Matlab offers this handy function vartestn to do that. In the documentation there ...
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34 views

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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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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71 views

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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398 views

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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63 views

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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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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247 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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123 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 ...
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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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2k views

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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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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225 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
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534 views

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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640 views

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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2k 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 ...
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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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484 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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2k 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 ...
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Levene test in R

I tested for equality of variance between two groups in R ...
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190 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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124 views

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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127 views

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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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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63 views

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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430 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 ...