Which test compares the means of two independent samples for a continuous outcome?

Which test compares the means of two independent samples for a continuous outcome?

• A. 2-sample t-test
• B. Paired t-test
• C. 1-sample t-test
• D. 1-proportion z-test

Answer: (A)

This question tests choosing the right test for comparing two independent groups on a continuous outcome. The two-sample t-test is the appropriate choice because it uses the means from two separate groups to determine if there is a statistically significant difference between their population means. It assumes the outcome is roughly normally distributed in each group (or relies on large sample sizes for the central limit theorem) and that observations are independent within and across groups. There are variations, like Welch’s t-test, that relax the equal-variance assumption. The other tests don’t fit this scenario: a paired t-test is for data that are linked or paired (before-and-after on the same subjects), not independent groups. A one-sample t-test checks whether the mean of a single group equals a known value. A one-proportion z-test analyzes a proportion from a single sample, not a mean on a continuous variable.

This question tests choosing the right test for comparing two independent groups on a continuous outcome. The two-sample t-test is the appropriate choice because it uses the means from two separate groups to determine if there is a statistically significant difference between their population means. It assumes the outcome is roughly normally distributed in each group (or relies on large sample sizes for the central limit theorem) and that observations are independent within and across groups. There are variations, like Welch’s t-test, that relax the equal-variance assumption.

The other tests don’t fit this scenario: a paired t-test is for data that are linked or paired (before-and-after on the same subjects), not independent groups. A one-sample t-test checks whether the mean of a single group equals a known value. A one-proportion z-test analyzes a proportion from a single sample, not a mean on a continuous variable.