STP Data Analysis 5

Question 1

A study reports a relative risk (RR) of 2.0 with a 95% CI of 1.2–3.5. What can be concluded?

Accepted Answer

The exposed group has twice the risk, and the result is statistically significant

Answer

RR = 2.0 means twice the risk in the exposed group; since the 95% CI does not include 1.0, the result is statistically significant.

Question 2

When calculating a non-parametric reference interval using the CLSI C28-A3 method with 120 samples, the 2.5th percentile is determined by:

Accepted Answer

Ranking data and selecting the 3rd lowest value

Answer

CLSI C28-A3 ranks the 120 values; the 2.5th percentile is the 3rd lowest value (rank 3 = 0.025 × 120).

Question 3

Which of the following best describes a Type II error in hypothesis testing?

Accepted Answer

Failing to reject a false null hypothesis

Answer

A Type II error (false negative) occurs when a false null hypothesis is not rejected; its probability equals beta (β).

Question 4

In a linear calibration curve, R² = 0.998 indicates:

Accepted Answer

99.8% of the variation in response is explained by the analyte concentration

Answer

R² (coefficient of determination) represents the proportion of variance in the dependent variable explained by the independent variable.

Question 5

Which statistical approach is used to adjust for multiple comparisons to control the false discovery rate?

Accepted Answer

Benjamini-Hochberg procedure

Answer

The Benjamini-Hochberg procedure controls the false discovery rate (FDR) and is less conservative than Bonferroni correction.

(STP) Scientist Training Programme Practice Test