FPGEE Biostatistics 3

Question 1

A meta-analysis reports an I² statistic of 75%. How should this be interpreted?

Accepted Answer

75% of the variance in effect sizes is due to heterogeneity rather than chance

Answer

I² quantifies the proportion of total variability in effect estimates attributable to heterogeneity across studies rather than sampling error.

Question 2

Which statistical test is most appropriate to compare median survival times between two independent treatment groups when data are censored?

Accepted Answer

Log-rank test

Answer

The log-rank test is specifically designed to compare survival distributions between groups while accounting for censored data.

Question 3

In a crossover clinical trial, what is the primary statistical concern that must be addressed?

Accepted Answer

Carryover effects from the first treatment period

Answer

Carryover (residual) effects occur when treatment from period 1 influences outcomes in period 2, violating the independence assumption.

Question 4

A drug reduces the absolute risk of myocardial infarction from 4% to 1%. What is the relative risk reduction?

Accepted Answer

75%

Answer

RRR = (Control risk − Treatment risk) / Control risk = (4% − 1%) / 4% = 75%.

Question 5

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 (β) is the failure to reject a false null hypothesis — concluding no effect exists when one actually does.

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