When I first introduce experimental design to students in AP Stats, we consider the diagram below.
A fun exercise in stats class is to locate stories in the media and comment on how the story's author interprets findings. Here's one such example from my morning Internet surfing.
Why Being Tired Can Make You Thinner and Healthier
Source: Yahoo News, Shine section
The following passage is taken from the article:
The urge to take care of our bodies when we're sleepy could be biological. “We proposed that people are more motivated to engage in healthful behavior when they are depleted and perceive their safety to be at stake," wrote study authors Monika Lisjak, assistant professor of marketing at Erasmus University in the Netherlands and Angela Y. Lee, professor of marketing at Northwestern University.
In the study, researchers asked subjects to read about the dangers of kidney disease and early detection, those with a family history included. Afterward, those who were feeling exhausted expressed a higher likelihood of being tested than their energized counterparts. In another study, subjects were asked to complete a survey on health and fitness, either before or after hitting the gym. After the survey, everyone was told to choose a gift of either sunblock or moisturizer. Those who had worked out were more likely to select the skin-saving sunblock.
Questions for students:
- Does the treatment suggest participants will get 'thinner' when tired?
- What is the author's motivation behind the wording in the article's title?
- What is the author's definition of 'healthier'?
- Could we design further research to confirm or disconfirm the author's claims?
- What implications do the results have on our daily lives?
- Is the source trustworthy? How would we make this decision?
- What would we need to know about the sampling method to make an informed decision about the results of this study?
- What would we need to know about the population of interest to make an informed decision about the results of this study?