Observational Studies and Experiments (Lesson 4.5)
Chapter 4 - Day 7
Explain the concept of confounding and how it limits the ability to make cause-and-effect conclusions.
Identify the treatments in an experiment.
Explain the purpose of a control group in an experiment.
You will start this lesson by showing this 3 minute video. Students will then be presented with several additional studies and asked to identify potential problems with each. We don’t expect students to be using all of the formal vocabulary in their discussion (unless maybe they have taken a psychology course). We will provide the formal vocabulary and definitions in the debrief of the activity and in the QuickNotes.
There is a lot of new vocabulary in this lesson. We decided not to put all the terms in the QuickNotes, as several of them appear nicely in the activity (placebo, single blind, double blind.
The big switch that is happening in this lesson is that we are moving away from the world of observational studies (Lessons 4.1 to 4.4) into the world of experiments (Lessons 4.5 to 4.7). The distinction here is that experiments intentionally impose treatments on subjects, rather than simply observing and collecting data. The advantage with an experiment is that we can often control for confounding variables, allowing us to establish a clear cause-and-effect relationship. We will get into the details for setting up a good experiment in the next lesson.