Six Sigma Green Belt Certification Practice Exam 2026 - Free Six Sigma Practice Questions and Study Guide

In a one-way ANOVA test, the degrees of freedom are calculated to assess the amount of variability in the data. Specifically, for a one-way ANOVA, you derive two types of degrees of freedom: one for the between-group variability and one for the within-group variability.

To clarify, the degrees of freedom between groups is calculated as the number of groups minus one (k - 1), where k is the total number of treatment groups. The degrees of freedom within groups is calculated as the total number of observations minus the number of groups (N - k), where N is the total sample size.

When conducting a one-way ANOVA, you find both degrees of freedom to perform the test correctly, but the essential focus is on how both contribute to a situation that generates a statistical outcome as a single value. Hence, when considering a case with k groups, an overall common interpretation leads to that singular comprehensive number—typically counted in exams as just the number of groups one less.

In summary, the correct answer reflects a foundational understanding of how the degrees of freedom in a one-way ANOVA are derived from the number of groups involved in the analysis, allowing for a proper interpretation of variance and significance.