# Problem 4 Sample Size for Confidence Interval forTwo Matched Samples Continuous OutcomeA small pilot study was conducted to compare cholesterollevels in individuals before and after a low-carbohydrate dietfor 6 months. The original study found an insignificantdecrease in cholesterol levels but only included six individualsIf the original study found a standard deviation of the differenceof 11.8:A. How many individuals would need to be included to detect a marginof error of 2.5 units?B. How many would be needed to account for 25% attrition?

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Problem 4

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Step 1

Preliminary calculation:

Using the EXCEL formula “=NORM.S.INV(1-(0.05/2))”, the z-value for 95% confidence level is obtained as 1.96.

Margin of error, E=2.5

Standard deviation of the difference, σd=11.8.

Step 2

A. Computation of number of individuals would need to be included to detect a margin of error of 2.5 units:

The number of individuals would need to...

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