Activity 12.1:

Statistical vs. Practical Significance

In each of the following, discuss whether the result or relationship is likely to be practically significant (PS), and then explain your reasoning.

1.A researcher finds that a particular relationship can occur by chance about 20 times in 100.

2.A researcher finds that students who use a new biology textbook recently purchased by the school district scored an average of 20 percent higher on an end-of-the-course examination.

3.A medical researcher finds that the use of a certain drug decreases the incidence of a life-threatening drug among a group of senior citizens by 3 percent.

4.A small appliance store finds that advertising in the local neighborhood newspaper increases her sales each week by 1 percent.

5.A new method of teaching five-year-olds how to tie their shoes results in their being able to do so three weeks earlier than similar five-year-olds not taught this method.

6.A researcher finds that a correlation of .18 has only a 1 in 1,000 likelihood of occurring by chance.