A clinical trial tests whether a new drug lowers blood pressure compared to placebo. The researchers hypothesize specifically that the drug will reduce systolic BP. The appropriate test should be:

• A Two-tailed test, because the drug could theoretically increase BP
• B One-tailed test, because the sample size is usually small
• C Two-tailed test, as regulatory agencies mandate two-tailed testing in all trials
• D One-tailed test, because the hypothesis predicts a specific direction of effect ✓

Explanation

When the research hypothesis predicts a specific direction (reduction in BP, not just any difference), a one-tailed test is statistically appropriate. Two-tailed tests are used when differences in either direction are considered meaningful. However, in practice, regulatory agencies often prefer two-tailed tests to be conservative.

Reference: Mahajan's Methods in Biostatistics, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.