Which test compares two independent groups on a single continuous outcome?

• A. Chi-square
• B. Pearson correlation
• C. Independent samples t-test
• D. Paired t-test

Answer: (C)

To compare two independent groups on a single continuous outcome, use the independent samples t-test. This test asks whether the average outcome differs between two unrelated groups, treating the observed difference in means as a statistic to be evaluated against the variability in the data. It relies on observations being independent, and the outcome being approximately normally distributed within each group (or having a large enough sample). If the two groups have similar variances, you can use the pooled estimate of variability; if variances differ, you use a version that does not assume equal variances (Welch’s t-test). This approach is specifically for continuous outcomes and independent groups. It’s not used for categorical data (that would be chi-square), not for assessing association between two variables (that would be Pearson correlation), and not for the same subjects measured twice or matched pairs (that would be a paired t-test).