Test the equality of variances across your groups.
Definition
Homogeneity of variances (homoscedasticity) is a prerequisite for classic ANOVA and the independent samples t-test. StatsLab offers Levene, Brown-Forsythe and Bartlett tests to evaluate this assumption.
When to use it
Before a one-way ANOVA to validate homoscedasticity
Before an independent samples t-test
To choose between classic ANOVA and Welch ANOVA
Requirements
At least 2 independent groups
Continuous dependent variable
Levene is robust to non-normality; Bartlett is sensitive
What StatsLab computes
Levene F statistic and p-value
Brown-Forsythe F statistic and p-value
Bartlett χ² statistic and p-value
Standard deviation and variance per group
Box plots per group
Worked example
Context : Comparing blood pressure variances across 3 treatment groups.
Result : Levene F(2, 57) = 1.24, p = 0.297
Interpretation : p > 0.05: the equality of variances hypothesis is not rejected. Classic ANOVA can be applied.