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Choosing a study design

Understand the model, recognise it in a stem, separate the look-alikes, then apply it.

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Watch it explainedYou want to study a rare cancer. Do you follow thousands of healthy people for decades? There is a much cheaper way, and it faces the other direction.

Per Grimes DA & Schulz KF An overview of clinical research: the lay of the land (The Lancet epidemiology series), 2002

Visual explanationUse the diagram to rebuild the concept from memory.
Direction of enquiry along time past future Cohort Exposure Outcome Case-control Exposure? Cases Cohort: pick by exposure, follow forward → incidence, relative risk Case-control: pick by outcome, look back → odds ratio
Direction of enquiry
Case-control looks Back from the Cases; Cohort Carries on forward.
References & guidelines
  • Grimes DA & Schulz KF, An overview of clinical research: the lay of the land (The Lancet epidemiology series) · 2002
  • Grimes DA & Schulz KF, Cohort studies: marching towards outcomes (The Lancet epidemiology series) · 2002
  • Grimes DA & Schulz KF, Compared to what? Finding controls for case-control studies (The Lancet epidemiology series) · 2002
  • Grimes DA & Schulz KF, Bias and causal associations in observational research (The Lancet epidemiology series) · 2002
  • Bland M, An Introduction to Medical Statistics (Oxford University Press)
  • Straus SE et al, Evidence-Based Medicine: How to Practice and Teach It

Checked against Grimes DA & Schulz KF An overview of clinical research: the lay of the land (The Lancet epidemiology series), 2002

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