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Question 698
Statistics → Epidemiology
Classification
Question
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Confidence interval
Question Stem
Two comparable studies report the same estimated treatment effect, but Study X has a wider 95% confidence interval than Study Y. What does the wider interval indicate?
Options
A
Greater precision
B
Greater statistical power
C
A more imprecise estimate
D
A larger treatment effect
E
Greater clinical significance
Explanation
A confidence interval provides a range within which the population parameter is estimated to lie with a specified level of confidence. A wide confidence interval indicates greater imprecision. Confidence intervals generally become narrower as sample size increases.
Option Validity
A) greater precision is associated with a narrower confidence interval.
B) interval width is primarily an expression of precision, not a direct measure of power.
D) width does not by itself indicate a larger treatment effect.
E) confidence-interval width does not establish clinical significance.
Further Reading
Review confidence intervals, precision and the effect of sample size on interval width.