Free PMP Exam Sample Question
Question:
You are currently performing process analysis for your project and you are following the steps outlined in the process improvement plan to identify needed improvements. You are examining problems that have surfaced, constraints experienced, and non-value-added activities identified during process execution. You are analyzing a sample of readings from the processes. If you need to decrease your confidence interval for your measurements, what should you do regarding the sample size you have selected?
A. You should increase the sample size to decrease the confidence interval
B. You should decrease the sample size to decrease the confidence interval
C. You should keep the same sample size since it does not have any effect on the confidence interval
D. You should keep the same sample size but decrease the number of measurements in the sample
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Hint: Confidence interval is the range of statistical values within which a result is expected to fall with a specific probability.
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Answer and Explanation:
The Correct Answer is A.
Confidence interval is the range of statistical values within which a result is expected to fall with a specific probability. A confidence interval (CI) is a particular kind of interval estimate of a population parameter. Instead of estimating the parameter by a single value, an interval likely to include the parameter is given. In this way, confidence intervals are used to indicate the reliability of an estimate. The smaller the confidence interval, the more accurate the measurement is. Therefore, if we want to decrease the confidence interval, i.e. we want a closer estimate, we need to increase the sample size.