The Randomized Controlled Trial (RCT)

  • Jørn Olsen
  • Kaare Christensen
  • Jeff Murray
  • Anders Ekbom
Part of the Springer Series on Epidemiology and Public Health book series (SSEH, volume 1)


Sometimes it may be possible to set up an experimental study, especially in clinical epidemiology. A new treatment may be compared with the standard treatment using one or more features of a randomized trial. The key, and obligatory, feature in the randomized trial is randomization, which is the allocation of two (or more) treatments that are to be compared by letting this allocation depend on the result of a random process like flipping a coin. By doing so, we let the selection of treatment be independent of the disease characteristics and other potential confounding factors.


Treatment Effect Potential Confounding Factor Neural Tube Defect Clinical Epidemiology Estimate Treatment Effect 
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    MRC Vitamin Study Research Group. Prevention of neural tube defects: results of the Medical Research Council Vitamin Study. Lancet 1991;338(8760):131–137.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2010

Authors and Affiliations

  • Jørn Olsen
    • 1
  • Kaare Christensen
    • 2
  • Jeff Murray
    • 3
  • Anders Ekbom
    • 4
  1. 1.School of Public HealthUniversity of California, Los AngelesLos AngelesUSA
  2. 2.Institute of Public HealthUniversity of Southern DenmarkOdense CDenmark
  3. 3.Department of Pediatrics, 2182 MedLabsUniversity of IowaIowa CityUSA
  4. 4.Department of MedicineKarolinska InstitutetStockholmSweden

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