A maintenance supervisor is comparing the standard version of an instructional booklet with one that has been claimed to be superior. An experiment is conducted in which 26 technicians are divided into two groups, provided with one of the booklets, then given a test a week later. For the 13 using the standard version, the average exam score was 72.0, with a standard deviation of 9.3. For the 13 given the new version, the average score was 80.2, with a standard deviation of 10.1. Assuming normal populations with equal standard deviations, and using the 0.05 level of significance, does the new booklet appear to be better than the standard version?

Question

A maintenance supervisor is comparing the standard version of an instructional booklet with one that has been claimed to be superior.  An experiment is conducted in which 26 technicians are divided into two groups, provided with one of the booklets, then given a test a week later.  For the 13 using the standard version, the average exam score was 72.0, with a standard deviation of 9.3. For the 13 given the new version, the average score was 80.2, with a standard deviation of 10.1.  Assuming normal populations with equal standard deviations, and using the 0.05 level of significance, does the new booklet appear to be better than the standard version?

PsyDAG · Answer

Ho: Standard = Superior
H1: Standard < Superior (one-tailed test)

Get Z score for difference between means

Z = (mean1 - mean2)/ Standard Error of Difference between means

SE of Difference = Sq root (SD1^2 + SD2^2)

See if Z score has less than .05 in smaller area in table at back of your Stats Text labeled something like "areas under normal distribution."

I'll let you do the calculations and make the decision.

I hope this helps. Thanks for asking.