Question

Which best illustrates the distinction between statistical significance and practical importance?
A. In 2016, 240 out of 400 statistics students at Oxnard Technical College sold their textbooks at the end of the semester, compared with 220 out of 330 students in 2015, a significant decrease.
B. Our new manufacturing technique has increased the life of the 80 GB USB AsimoDrive external hard disk significantly, from 240,000 hours to 250,000 hours.
C. In 50,000 births, the new vaccine reduced the incidence of infant mortality in Morrovia significantly from 14.2 deaths per 1000 births to 10.3 deaths per 1000 births.
D. The new Sky Penetrator IV business jet's cruising range has increased significantly from 3,975 miles to 4,000 miles.

Answer 1

Answer:

The distinction between statistical significance and practical importance is best illustrated by:

C. In 50,000 births, the new vaccine reduced the incidence of infant mortality in Morrovia significantly from 14.2 deaths per 1000 births to 10.3 deaths per 1000 births.

Step-by-step explanation:

                                   Current state     Previous state     Change

A.  Textbooks sold      240/400 (0.6)   220/330 (0.67)     0.07

B.  Life of hard disk     250,000 hrs     240,000 hrs         0.04

C.  Infant mortality      10.3 per 1000    14.2 per 1000       0.27

D.  Cruising range      4,000 miles       3,975 miles          0.006          

Statistical significance, which depends on the p-value established before the test, relates to whether an effect exists, while practical significance determines the magnitude or size of the effect.  A statistical test cannot tell whether the magnitude is large enough to be important.  Mathematically, the change can be determined, which establishes the practical significance or importance of the change.