FPGEE Biostatistics 4

Question 1

Berkson's bias is a specific form of selection bias most commonly associated with which study design?

Accepted Answer

Hospital-based case-control studies

Answer

Berkson's bias occurs when both cases and controls are drawn from hospitalized patients, distorting the true association because hospitalization rates differ by exposure and disease.

Question 2

A study of a new antibiotic uses intention-to-treat (ITT) analysis. Which statement best describes this approach?

Accepted Answer

All randomized patients are analyzed in their originally assigned groups regardless of adherence

Answer

ITT analysis preserves the benefits of randomization and gives a conservative, real-world estimate of treatment effect by including all randomized subjects.

Question 3

Which measure of central tendency is most resistant to outliers in a skewed pharmacokinetic dataset?

Accepted Answer

Median

Answer

The median is the middle value and is not influenced by extreme values (outliers), making it robust for skewed distributions.

Question 4

A diagnostic test for a rare disease (prevalence 1%) has sensitivity 99% and specificity 99%. What is the approximate positive predictive value?

Accepted Answer

Approximately 50%

Answer

PPV ≈ TP/(TP+FP); with 1% prevalence and 99% specificity, false positives (~1% of 9,900 = 99) nearly equal true positives (~99), giving PPV ≈ 50%.

Question 5

In multiple linear regression, what does the R² value represent?

Accepted Answer

The proportion of variance in the outcome explained by all predictors combined

Answer

R² (coefficient of determination) represents the proportion of total variance in the dependent variable that is explained by the regression model.

FPGEE Exam Practice Test

FPGEE Exam Practice Test

FPGEE Biostatistics 4