A national manufacturer of ball bearings is experimenting with two different processes for producing precision ball bearings. It is important that the diameters be as close as possible to an industry standard. The output from each process is sampled and the average error from the industry standard is calculated. The results are presented below: The researcher is interested in determining whether there is evidence that the two processes yield different average errors.
This example is what type of test?
A) One sample test of means.
B) Two sample test of means.
C) Paired t-test.
D) Test of proportions.

Question

A national manufacturer of ball bearings is experimenting with two different processes for producing precision ball bearings. It is important that the diameters be as close as possible to an industry standard. The output from each process is sampled and the average error from the industry standard is calculated. The results are presented below:  The researcher is interested in determining whether there is evidence that the two processes yield different average errors.
This example is what type of test?
A) One sample test of means. 
B) Two sample test of means. 
C) Paired t-test. 
D) Test of proportions.

Quizplus · Accepted Answer

The experiment involves two different processes for producing the balls, and the researcher is interested in comparing the average errors between the two processes. Therefore, a two sample test of means is the appropriate choice. Option A (One sample test of means) would be appropriate if the researcher was comparing the average error from a single process to a known industry standard. Option C (Paired t-test) would be appropriate if the data was collected in pairs for the same items, such as before and after measurements. Option D (Test of proportions) would be appropriate if the data involved categorical variables and the researcher was interested in comparing proportions or percentages.

A National Manufacturer of Ball Bearings Is Experimenting with Two