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Question: 6.87 NFL player survey. Researchers at the University of Pennsylvania鈥檚 Wharton Sports Business Initiative collaborated with the National Football League Players Association (NFLPA) to produce the first NFL Player Survey. Of the 1,696 active NFL players, 1,355 (almost 80%) responded to the survey. One of the survey questions asked, 鈥淲ho is the coach鈥攑rofessional, college, or high school鈥攖hat has been the most influential in your career?鈥 Of the 1,355 respondents, 759 selected an NFL (professional) coach.

a. Construct a 95% confidence interval for the true proportion of active NFL players who select a professional coach as the most influential in their careers.

b. Why is it necessary to use the continuity correction factor in the construction of the interval, part a?

c. Give a practical interpretation of the interval, part a.

Short Answer

Expert verified
  1. The required confidence interval is (0.5481, 0.5721).
  2. The finite population correction factor should be included in the standard error calculation for true proportion.
  3. It is 95% confident that the true proportion of active NFL players who selected a professional coach as most influential is between 0.548 and 0.572.

Step by step solution

01

Given information

The number of active National Football League (NFL) Players is

The sample size is

Let x denotes the (NFL) candidates who were selected by the coach that is

02

(a) Calculating 95% confidence interval

The proportion of active NFL players who select a professional coach as the most influential in their careers is calculated using the following formula,

p^=xn

Therefore

p^=7591355=0.5601

The 95% confidence interval for the true proportion is obtained by using the following formula

p^2p^1-p^nN-nN

p^2p^1-p^nN-nN=0.560120.56011-0.560113551696-13551696=0.56010.012=0.5481,0.5721

Hence, the required confidence interval is (0.5481, 0.5721).

03

(b) Explanation of continuity correction  

When the sample size is large relative to the number of measurements in the population, the standard error of the estimators of p should be multiplied with a finite population correction factor. Let鈥檚 find the value of ; if it is greater than the finite population correction factor, it should be included in the standard error calculation.

nN=13551696=0.7989

Here it is observed that thenN=0.7989>0.05finite population correction factor should be included in the calculation of the standard error for true proportion.

04

(c) Interpretation

The 95% confidence interval is (0.548, 0.572). Thus, it is 95% confident that the true proportion of active NFL players who selected a professional coach as most influential is between 0.548 and 0.572.

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