3 | FRQ (Part A: Sampling) | Practice Sessions | AP Statistics

Luke Wilcox, an AP Statistics teacher at East Kentwood High School, introduces an AP Daily Practice Session focused on data collection. He encourages students to download and attempt two free response questions before watching the video to check their work. The session will cover the identification of treatments, experimental units, and response variables in an experiment involving a dermatologist's study on acne treatment with identical twins.

The video script explains the design of an experiment where a dermatologist investigates a new acne treatment using 36 pairs of identical twins. Each subject receives either a new drug or a placebo, and their acne improvement is measured on a scale. The script clarifies the treatments, experimental units, and response variable. It emphasizes the importance of identifying individual subjects as experimental units rather than pairs and discusses the statistical advantage of using a matched pairs design over a completely randomized design to control for initial acne severity variance.

The script describes how to randomly assign treatments to subjects in a matched pairs design using the example of a dermatologist's experiment. It suggests using a coin toss to determine which twin receives the new drug or placebo, and emphasizes the need to repeat this process for all pairs. Alternative methods like random number generators or notecards are also mentioned. The explanation ensures that the random assignment process is clear and consistent across all pairs of twins.

The script discusses a study reported in a local newspaper that found a strong association between smoking and Alzheimer's disease. It identifies the explanatory variable as the degree of cigarette smoking and the response variable as Alzheimer's status. The study is confirmed as observational, not experimental, since the researchers did not impose smoking levels on subjects. The script also introduces the concept of confounding variables, specifically exercise status, which could influence both smoking behavior and Alzheimer's risk, thus potentially affecting the study's conclusions.

The script delves into the role of exercise status as a possible confounding variable in the study linking smoking to Alzheimer's disease. It explains that exercisers might be more health-conscious and less likely to smoke, thus connecting exercise status to the explanatory variable of smoking. It also suggests that regular exercise could independently reduce Alzheimer's risk, affecting the response variable. The script concludes by highlighting how the association between smoking and Alzheimer's could be influenced by the confounding effect of exercise, complicating the interpretation of the study's findings.