Observational Studies: Learn It 2

Observational Study vs. Experiment

Video Placement

[Worked Example/Perspective: a 3-instructor video that gives pointers on how to distinguish between an experiment and an observational study in the style of Questions 5 and 6]

Now you try identifying which type of study was used given a brief description. For Questions 5 and 6, select the most correct statement for the given scenario.

question 5

5) A geography professor divides his classroom into in-state students and out-of-state students and quizzes them on local landmarks.

  1. a) This is an experimental study since the professor has divided his class into two groups.
  2. b) This is an experimental study since the professor has not assigned a treatment.
  3. c) This is an observational study since the professor has divided his class into two groups.
  4. d) This is an observational study since the professor has not assigned a treatment.

question 6

6) A pharmaceutical company develops a new blood pressure medication and recruits 300 participants for a study. For this study, 100 people are randomly assigned to the new medication, 100 are randomly assigned to the old medication, and 100 are given a placebo (no medication). Blood pressure levels of the participants are monitored over time.

  1. a) This is an experimental study since the company randomly assigns participants to groups and provides a treatment to each group.
  2. b) This is an experimental study since the blood pressure levels of the participants are monitored over time.
  3. c) This is an observational study since the company randomly assigns participants to groups and provides a treatment to each group.
  4. d) This is an observational study since the blood pressure levels of the participants are monitored over time.

Looking ahead

In the next class, you will be discussing characteristics of a very recent study from the Centers of Disease Control and Prevention. In this study, researchers followed 3,950 health care personnel, first responders, and other essential frontline workers for 13 consecutive weeks to observe how effective Messenger RNA COVID-19 vaccines have been in a real-world setting. The study can be found here: https://www.cdc.gov/mmwr/volumes/70/wr/mm7013e3.htm.

question 7

Answer the following questions about the study.

 

Part A: Who is being studied?

 

Part B: What is being observed for each participant in the study?