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Research Methods in Healthcare Epidemiology and Antimicrobial Stewardship—Quasi-Experimental Designs

Published online by Cambridge University Press:  07 June 2016

Marin L. Schweizer*
Department of Internal Medicine, Carver College of Medicine, University of Iowa, Iowa City, Iowa Center for Comprehensive Access and Delivery Research and Evaluation, Iowa City VA Health Care System, Iowa City, Iowa
Barbara I. Braun
Department of Health Services Research, The Joint Commission, Oakbrook Terrace, Illinois
Aaron M. Milstone
Department of Pediatrics, Division of Pediatric Infectious Diseases, Johns Hopkins University School of Medicine, Baltimore, Maryland Department of Hospital Epidemiology and Infection Control, Johns Hopkins Hospital, Baltimore, Maryland
Address correspondence to Marin L. Schweizer, PhD, Iowa City VA Health Care System (152), 601 Hwy 6 West, Iowa City, IA 52246 (


Quasi-experimental studies evaluate the association between an intervention and an outcome using experiments in which the intervention is not randomly assigned. Quasi-experimental studies are often used to evaluate rapid responses to outbreaks or other patient safety problems requiring prompt, nonrandomized interventions. Quasi-experimental studies can be categorized into 3 major types: interrupted time-series designs, designs with control groups, and designs without control groups. This methods paper highlights key considerations for quasi-experimental studies in healthcare epidemiology and antimicrobial stewardship, including study design and analytic approaches to avoid selection bias and other common pitfalls of quasi-experimental studies.

Infect Control Hosp Epidemiol 2016;1–6

SHEA White Papers
© 2016 by The Society for Healthcare Epidemiology of America. All rights reserved 

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