Question

Write a problem. In this exercise, I would like you to think of a statistical analysis you would like to do ( preferably at your work). That is, you will like to compare population means or do a hypothesis testing. Please write carefully the problem. Make sure you justify all your assumptions. Propose a method of solving the problem. Be as precise as possible.

Answer 1

Comparison of population means:

Consider 174 customers of Company A and 355 customers of Company B were randomly selected and were asked to rate their cable companies on a five-point scale 1-5, with 1 being least satisfied and 5 most satisfied. The survey results are are as follows:

Construct a point estimate and 99% confidence interval for difference of population means, that is difference in average satisfaction levels of customers of the two companies as measured on this five-point scale.

The result is:

Thus, the average customer satisfaction level for Company A is 0.27 points higher on this five-point scale than it is for Company B.

H0: There is no difference between the two population means

Ha: There is difference between two population means

The 99% confidence interval or 1% level of significance result in z-statistic being 2.576 for two-tailed

The test result is:

Thus, at 99% confidence level, the difference in the population means lies in the interval [0.15,0.39]

Thus, one can conclude that statistically average level of customer satisfaction for Company A is between 0.15 and 0.39 points higher, on this five-point scale, than that for Company A.