1. What is Levene’s Test?
Levene’s Test is a statistical test used to assess the equality of variances (homogeneity of variance) across multiple groups. It checks whether different samples have similar variances, which is an important assumption for parametric tests like ANOVA and t-tests.
2. How Levene’s Test Works:
- If the variance among groups is similar, the test will not be significant.
- If the variances are significantly different, the test will be significant.
3. Hypotheses:
- Null Hypothesis (H0): The variances of all groups are equal.
- Alternative Hypothesis (Ha): At least one group has a different variance.
4. Interpreting the Results:
- If p > 0.05, fail to reject H0 → Variances are equal (homogeneity assumption holds).
- If p ≤ 0.05, reject H0 → Variances are significantly different (homogeneity assumption is violated).
5. Steps of Levene’s Test in SPSS
- Make sure selecting the right data
In this sample data, Group is the independent variable, and Score is the dependent variable. We want to test if the variance between these 3 groups are significantly different.
- Click Analyze -> Descriptive Statistics -> Explore
- Drag Score into Dependent List and drag Group into the Factor List box.
- Click PLots and on the pop-up windown, make sure “Power estimation” is checked. Click Continue in the pop-up window then click OK in the main Explore window.
- Focus on the table of Test of Homogeneity of Variance in the output result
We are going to focus on the first row, namely Based on Mean. As we can see, the p-value is 0.832, which is greater than 0.05. As mentioned earlier, when p > 0.05, we fail to reject H0 → Variances are equal (homogeneity assumption holds).