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.
Questions tagged [levenes-test]
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How to use Levene test function in R?
I'm a newbie to statistics and R and I have a trouble with using Levene function (I would like to check the equality of variance of two samples).
The documentation says that I should run:
levene.test(y, group)
But I have no idea what I should put…
Jakub
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Bartlett's test vs Levene's test
I am currently trying to address violations to ANOVA assumptions. I have used Shapiro-Wilk to test normality, and have dabbled with both Levene's test and Bartlett's test of variance equality. I have since log transformed my data to try and remedy…
Clarice
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Interpretation of the p-values produced by Levene's or Bartlett's test for homogeneity of variances
I have run Levene's and Bartlett's test on groups of data from one of my experiments to validate that I am not violating ANOVA's assumption of homogeneity of variances. I'd like to check with you guys that I'm not making any wrong assumptions, if…
levesque
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"One-tailed" Levene Test
F-tests can be two-tailed (to test that $s_1^2 \ne s_2^2$) or one-tailed (to test that $s_1^2 > s_2^2$).
How can I modify Levene/Brown-Forsythe to be "one-tailed", that is, to test $s_1^2 > s_2^2$ instead of $s_1^2 \ne s_2^2$?
Here is a demo:
The…
jmilloy
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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 yet have the data but I know for sample1, n=167…
Erika_Hammerl246
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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 simple t-test for this (the t.test R function), but…
Germán Ruelas
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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't assume anything about the population. Since it…
user1561358
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Significant output in Levene's test for equality of variances in MANOVA; what to do?
I want to perform a MANOVA in SPSS as follows: i have a independent variable that consists of three groups (- of which the group sizes are not equal), and six dependent variables.
When checking the Levene's test for equality of error variances,…
TvBalkom
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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 'true' underlying effect.
The dangers of use of…
Josh Blake
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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 to be having at least one group with more than 1…
Karolis Koncevičius
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Is Levene's test necessary?
My friend told me to use Levene's test to check the assumption of homoskedasticity before applying the two sample t-test. I think most people that use linear models don't do that. They check the residual plot to eye ball it instead, and it would be…
oneko
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Effect size for difference between variances / Levene's test
I have tested a hypothesis of equal variances (using Levene's test), and would like to report an effect size alongside the significance test. Unfortunately, I cannot seem to find any references to a way to calculate an effect size for differences in…
simoncolumbus
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Do I have a justified reason to exclude a non-significant covariate from my ANCOVA? How interesting is unequal variance?
I am comparing glutamate concentrations across groups (2 groups). Age was significantly correlated with glutamate while IQ was not.
If there is a significant difference in variance between groups. Is this meaningful and what can I conclude from…
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Is an F-test for equality of variance appropriate for a very large dataset?
I have a dataset with about 500,000 subjects and I am trying to establish whether the variance is equal. I first performed an F-test but then I realised the data is slightly skewed with kurtosis. So then I went with the Brown-Forsythe variation of…
googleplex101
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What's the rationale behind the degrees of freedom in Levene's test?
I've been reading the Wikipedia page for Levene's test, and it cites the degrees of freedom as (k - 1, N - k), where k is the number of different groups to which the sampled cases belong, and N is the total number of cases in all groups. However,…
user1205901 - Reinstate Monica
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