Certified Six Sigma Black Belt Exam Hypothesis Testing 4

Question 1

Which condition must be met to validly use a two-sample t-test with pooled variance?

Accepted Answer

Population variances must be assumed equal

Answer

The pooled two-sample t-test assumes the two populations have equal variances; use Welch's t-test when this assumption fails.

Question 2

A team detects a statistically significant difference in cycle times but the improvement is only 0.5 seconds on a 10-minute process. Which concept explains why this finding may not matter?

Accepted Answer

Practical significance / effect size

Answer

Practical significance considers whether the detected effect is large enough to be meaningful in context, independent of statistical significance.

Question 3

The Kruskal-Wallis test is the non-parametric equivalent of which parametric test?

Accepted Answer

One-way ANOVA

Answer

Kruskal-Wallis tests for differences in median ranks across three or more independent groups, analogous to one-way ANOVA.

Question 4

A Black Belt runs a hypothesis test and obtains p = 0.12 with α = 0.05. The correct conclusion is:

Accepted Answer

Fail to reject H₀; insufficient evidence to conclude a difference

Answer

Failing to reject H₀ means there is insufficient evidence to support H₁; it does not prove H₀ is true.

Question 5

In a two-tailed hypothesis test with α = 0.05, the critical region is located:

Accepted Answer

Split equally (2.5%) in each tail

Answer

A two-tailed test divides α equally between both tails, placing 2.5% in each tail for α = 0.05.

Certified Six Sigma Black Belt Exam Practice Test

Certified Six Sigma Black Belt Exam Practice Test

Certified Six Sigma Black Belt Exam Hypothesis Testing 4