# 15.10: Statistical Literacy

Skills to Develop

• Testing an Alzheimer's Drug

A research design to compare three drugs for the treatment of Alzheimer's disease is described here. For the first two years of the study, researchers will follow the subjects with scans and memory tests.

Example  $$\PageIndex{1}$$: what do you think?

Assume the data were analyzed as a two-factor design with pre-post testing as one factor and the three drugs as the second factor. What term in an ANOVA would reflect whether the pre-post change was different for the three drugs?

Solution

It would be the interaction of the two factors since the question is whether the effect of one factor (pre-post) differs as a function of the level of a second factor (drug).

### Weight Loss and Cancer Risk

An experiment on risk factors for cancer had four conditions related to weight loss. Quoting the web page description:

"McTiernan and her colleagues randomly assigned 399 overweight and obese postmenopausal women to one of four groups — dieting plus exercise, dieting only, exercise only or a control group not required to do either."

Example  $$\PageIndex{2}$$: what do you think?

What type of ANOVA design was used?

Solution

There are two between-subjects factors: Diet (yes or no) and Exercise (yes or no) resulting in the four conditions. The design is a $$2 \times 2$$ factorial design.

### Contributor

• Online Statistics Education: A Multimedia Course of Study (http://onlinestatbook.com/). Project Leader: David M. Lane, Rice University.