Research methodsLesson 2 of 2 in the course Data collection

Observational Studies: Designs, Bias, and Causal Inference

5 flashcards · 5 quiz questions · 5 match pairs · 4 fill-in sentences · English

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Summary

Observational studies help researchers investigate questions when they cannot or should not assign people or communities to different conditions. This lesson introduces what makes a study observational, why researchers use this approach, and the main study types.

An observational study draws conclusions by observing subjects or situations without controlling the independent variable. Researchers do not decide who receives a treatment or belongs to a particular group. Instead, they study groups or exposures that already exist or arise naturally.

All flashcards

What is an observational study?
A study that investigates variables as they occur without the researcher assigning subjects to treatment or control conditions.
How does an RCT assign subjects differently from an observational study?
An RCT uses random assignment to form treatment and control groups; an observational study examines groups or exposures not assigned by the researcher.
What is a case-control study?
A study that compares groups with different outcomes and examines whether they differ in a suspected exposure or causal attribute.
What distinguishes cross-sectional and longitudinal studies?
A cross-sectional study collects data at one point in time; a longitudinal study repeats observations over an extended period.
What is target trial emulation?
An approach that uses observational data and a specified design to approximate the question and structure of an RCT.

Quiz questions

  1. When does confounding complicate interpretation of an exposure-outcome relationship?Answer: When other factors are related to both the exposure and the outcome.
  2. What is selection bias in an observational study?Answer: A distortion caused by how subjects or observations are chosen.
  3. How can an omitted variable distort an observational study's conclusions?Answer: If it relates to both the studied exposure and outcome, it can distort their apparent relationship.
  4. What is the purpose of target trial emulation?Answer: To use observational data and a specified design to approximate an RCT's question and structure.
  5. What conclusion can observational evidence support on its own?Answer: It can reveal patterns and inform decisions, but does not by itself prove causation.

Based on the Wikipedia article Observational study, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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