Increasing the sample size while keeping everything else the same has what effect on the width of a confidence interval?
Answer and explanation
Correct answer: D. It makes the interval narrower
- Step 1: The standard error falls as n rises. Step 2. A smaller standard error gives a narrower interval. Answer: narrower. Why not the others: The standard error is inversely proportional to the square root of sample size n; increasing n decreases standard error and yields a narrower confidence interval.
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