Question

To compare the effectiveness of a media campaign - via radio ads, billboards, and ads on social media websites - to reduce the incidence of impaired driving, a police chief inspected data from 60 randomly chosen CheckStops at varying locations.Thirty of these were before the launch of this campaign, 30 were after the media campaign had been running for a months time. Use α=0.05α=0.05 for all calculations.

For each CheckStop randomly chosen, the number of people charged with impaired driving was recorded:
Prior: 8, 11, 10, 4, 9, 6, 4, 9, 3, 10, 2, 9, 4, 6, 5, 4, 1, 8, 5, 7, 3, 7, 4, 8, 4, 11, 4, 8, 3, 9
After: 8, 3, 3, 3, 5, 2, 7, 6, 6, 5, 3, 9, 7, 8, 7, 5, 6, 5, 4, 3, 5, 3, 4, 3, 3, 4, 6, 4, 8, 4

Let μBeforeμBefore represent the mean number of impaired driving charges at a checkstop prior to the launch of the campaign, and μAfterμAfter be the mean number of impaired driving charges at a checkstop after the campaign has been running for a month.

(a) Does this data suggest that the variation in the number of impaired driving charges before the campaign is equal to the variation in the number of impaired driving charges after the campaign has been running for a month?
From the appropriate statistical test, find the value of the test statistic. Using at least two decimals in your answer.
Test Statistic =

(b) Report the p-value of the test you ran in (a), using at least three decimals in your answer.

(c) find a 95% confidence interval for the difference between the mean number of impaired driving charges before the media campaign and the mean number of impaired driving charges after the media campaign has been running for a month, μBefore−μAfterμBefore−μAfter.

Answer 1

Data with difference would be as followed:

Using the "AVERAGE" function and "STDEV" function we have calculated the standard deviation and mean in excel you can also calculate manually using the simple formula of mean and standard deviation.

i.e., Mean= summation of di / n

S.d= sqrt(summation(di- d-bar)^2/n-1)

a), b), c) are defined in sequence in the below file: