The article "Cops Get Screened for Digital Dirt" (USA Today, Nov. 12,2010 )
summarizes a report on law enforcement agency use of social media to screen
applicants for employment. The report was based on a survey of 728 law
enforcement agencies. One question on the survey asked if the agency routinely
reviewed applicants' social media activity during background checks. For
purposes of this exercise, suppose that the 728 agencies were selected at
random and that you want to use the survey data to decide if there is
convincing evidence that more than \(25 \%\) of law enforcement agencies review
applicants' social media activity as part of routine background checks.
a. Describe the shape, center, and spread of the sampling distribution of
\(\hat{p}\) for samples of size 728 if the null hypothesis \(H_{0}: p=0.25\) is
true.
b. Would you be surprised to observe a sample proportion as large as
\(\hat{p}=0.27\) for a sample of size 728 if the null hypothesis \(H_{0}: p=0.25\)
were true? Explain why or why not.
c. Would you be surprised to observe a sample proportion as large as
\(\hat{p}=0.31\) for a sample of size 728 if the null hypothesis \(H_{0}: p=0.25\)
were true? Explain why or why not.
d. The actual sample proportion observed in the study was \(\hat{p}=0.33 .\)
Based on this sample proportion, is there convincing evidence that more than
\(25 \%\) of law enforcement agencies review social media activity as part of
background checks, or is this sample proportion consistent with what you would
expect to see when the null hypothesis is true?