If you decide you want a smaller margin of error for a confidence interval, should you increase or decrease the sample size?
A) Increase B) Decrease C) Do not need to change
The correct answer is
- A) Increase
Reasoning:
We have,
Margin of error = z*/sqrt(n)
where,
= standard deviation
n = sample size
Thus, margin of error in inversely proportional to square root of sample size.
i.e. If Margin of error has to be reduced sample size needs to be increased and vice versa
Thus, Option A is correct answer.
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