To find the effect of a recent policy change on employee morale, a large corporation decides to conduct an opinion survey, asking N randomly selected employees whether they are satisfied with the new policy. How many employees must be sampled in order to guarantee a sampling error (95% confidence interval) within +/− 3%? (Hint: Recall class discussion of sample size to meet error margin requirements for unknown proportions.) A survey is conducted, using the value of N chosen in part a. This survey reveals that 62.5% of the sampled employees are satisfied with the new policy. What is the 95% confidence interval for p, the proportion of all company employees that are satisfied with the new policy? What is the 99% confidence interval for p?   Does the 95% confidence interval suggest that a majority of employees are satisfied with the policy? Discuss in 1 or 2 sentences.

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  1. To find the effect of a recent policy change on employee morale, a large corporation decides to conduct an opinion survey, asking N randomly selected employees whether they are satisfied with the new policy.
  1. How many employees must be sampled in order to guarantee a sampling error (95% confidence interval) within +/− 3%? (Hint: Recall class discussion of sample size to meet error margin requirements for unknown proportions.)

  2. A survey is conducted, using the value of N chosen in part a. This survey reveals that 62.5% of the sampled employees are satisfied with the new policy.

    • What is the 95% confidence interval for p, the proportion of all company employees that are satisfied with the new policy?

    • What is the 99% confidence interval for p?

     

  3. Does the 95% confidence interval suggest that a majority of employees are satisfied with the policy? Discuss in 1 or 2 sentences.

Expert Solution
Step 1

In order to guarantee a sampling error (95% confidence interval) within +/− 3% :

 

 

The Confidence interval should be obtained as :

p^ ± Zα2=0.025 p^(1-p^)n

By the problem ,

 Zα2=0.025 p^(1-p^)n < 0.03=1.96 × 0.5(1-0.5)n < 0.03            , [  at p^ = 0.5 the expression 0.5(1-0.5)n is maximized ]= 0.5(1-0.5)n < 0.015306= 0.25n2 < 0.000234= n2 > 1068.376= n > 32.686n = 33 

 

Therefore, 33 employees must be sampled 

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