Equal standard deviations

Definition

Equal standard deviations mean that the variability or dispersion of data points in different groups are the same. This assumption is critical for certain statistical tests to provide valid results.

5 Must Know Facts For Your Next Test

1. In One-Way ANOVA, equal standard deviations across groups are an important assumption known as homogeneity of variances.
2. The Levene's test or Bartlett's test can be used to check if standard deviations are equal across groups.
3. If the assumption of equal standard deviations is violated, results from ANOVA may not be reliable.
4. Transformations or alternative statistical methods like Welch’s ANOVA can be used if standard deviations are not equal.
5. Graphical methods such as residual plots can also help assess whether standard deviations are equal.

Review Questions

Related terms

Homogeneity of Variance:

The assumption that different samples have the same variance, often tested before performing an ANOVA.

Levene's Test:

A statistical test used to assess the equality of variances for a variable calculated for two or more groups.

Welch’s ANOVA: \text{A version of ANOVA that does not assume equal variances and provides a more robust analysis when variances are unequal.}