Session 3: Observational Studies

Facilitator: Bob Goodman

Learning Objectives

  • Identify and contrast observational study designs.

  • Identify the advantages and disadvantages of observational studies vis-à-vis randomized trials.

  • Identify the methods used in observational studies to address confounding.

  • Explain to your significant other what is meant by "adjustment."


You are seeing a 40-year-old mildly obese woman with hypertension for a routine visit. Today, sitting in your office with a 5 lb bag of mixed nuts in her lap, she tells you that she recently read a story in the Post, which said that eating nuts could reduce her risk of a heart attack. The story, she tells you, reported that a “Harvard study” showed that people who eat nuts every day are 20% less likely to die than people who don’t eat nuts. Though she has stopped going to the gym, she does say she is smoking less—mostly because she is eating nuts all the time. Her blood pressure today is 136/84, and she has gained 4 lbs since her last visit. She offers you some nuts and asks if you are familiar with the study. You decline the nuts and tell her that you heard about the study but haven’t read it. You discuss smoking cessation, encourage her to resume exercising, and tell her you will take a look at the report.



  • There is no homework for this session.