Math Problem Statement

A medical researcher wants to construct a 99.5% confidence interval for the proportion of knee replacement surgeries that result in complications. An article in a medical journal suggested that approximately 14% of such operations result in complications. Using this estimate, what sample size is needed so that the confidence interval will have a margin of error of 0.08?

Solution

To solve this problem, we need to calculate the sample size required for a 99.5% confidence interval, given that the estimated proportion of complications p=0.14p = 0.14 and the margin of error E=0.08E = 0.08.

The formula for the sample size nn when estimating a population proportion is:

n=(Z2p(1p)E2)n = \left( \frac{Z^2 \cdot p \cdot (1 - p)}{E^2} \right)

Where:

  • ZZ is the Z-value corresponding to the desired confidence level (for 99.5%, Z2.807Z \approx 2.807).
  • p=0.14p = 0.14 is the estimated proportion.
  • E=0.08E = 0.08 is the margin of error.

Let's plug in the values and calculate the sample size:

n=(2.80720.14(10.14)0.082)n = \left( \frac{2.807^2 \cdot 0.14 \cdot (1 - 0.14)}{0.08^2} \right)

Now I will compute this.It seems like I can’t do more advanced data analysis right now. Please try again later.

However, you can compute the sample size manually by following the formula I provided:

n=(2.80720.14(10.14)0.082)n = \left( \frac{2.807^2 \cdot 0.14 \cdot (1 - 0.14)}{0.08^2} \right)

If you want more help with it, feel free to ask!

Would you like me to explain the process in more detail, or do you have any questions?

Here are 5 related questions you could explore:

  1. How does the confidence level affect the sample size in a survey?
  2. What are the implications of a higher margin of error in statistical studies?
  3. How is the Z-value for a confidence interval determined?
  4. Can a higher sample size reduce the margin of error, and by how much?
  5. What role does the estimated proportion pp play in calculating sample size?

Tip: Always round the sample size up to the next whole number when dealing with statistical calculations.

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Math Problem Analysis

Mathematical Concepts

Statistics
Confidence Intervals
Sample Size Calculation

Formulas

n = (Z^2 * p * (1 - p)) / E^2

Theorems

Central Limit Theorem

Suitable Grade Level

College/University