Question: A firm is considering requiring its secretaries to take a business typing class. 12 secretaries are randomly selected. Each is tested before ( B ) enrolling in the class, and then tested again 6 months after ( A ) passing the class. The following test results are reported in words per minute, adjusted for errors.

Secretary WPM B efore WPM A fter

Alice 40 45

Bob 30 40

Carol 65 65

Daniel 70 65

Evelyn 45 50

Frank 45 40

Grace 55 55

Harry 60 65

Irene 75 75

Jack 35 40

Kathy 40 50

Larry 50 55

1. At the 5% level of significance, does the sample data indicate that the typing class improves typing performance? BE SURE TO INDICATE WHICH WAY YOU ARE SUBTRACTING.
2. Estimate the population mean difference with a 90% confidence interval estimate.
3. What are the advantages of using the same secretaries for both samples? What factors affecting typing performance might still not be accounted for using this procedure?
4. What is the p-value for your hypothesis test?
5. Perform the hypothesis test again, assuming that the samples are INDEPENDENT rather than dependent. Assume that the variances are equal and use FORMULA G from my Econ 262 Formulas handout (use the POOLED standard deviation).
6. What is the p-value for this second hypothesis test.

Price: $2.99

Solution: The downloadable solution consists of 5 pages
Deliverable: Word Document