title: Quasi-experimental study designs series-paper 7: assessing the assumptions.
abstract: Quasi-experimental designs are gaining popularity in epidemiology and health systems research-in particular for the evaluation of health care practice, programs, and policy-because they allow strong causal inferences without randomized controlled experiments. We describe the concepts underlying five important quasi-experimental designs: Instrumental Variables, Regression Discontinuity, Interrupted Time Series, Fixed Effects, and Difference-in-Differences designs. We illustrate each of the designs with an example from health research. We then describe the assumptions required for each of the designs to ensure valid causal inference and discuss the tests available to examine the assumptions.
authors.affiliation: Institute of Public Health, Faculty of Medicine, Heidelberg University, Heidelberg, Germany; Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, USA; Africa Health Research Institute, Somkhele, South Africa. Electronic address: tbaernig@hsph.harvard.edu.
authors.forename: Till
authors.initials: T
authors.lastname: Bärnighausen
authors.affiliation: Francis I. Proctor Foundation, University of California San Francisco, San Francisco, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Oldenburg
authors.affiliation: Department of Medicine, University of Ottawa, Ottawa, Canada.
authors.forename: Peter
authors.initials: P
authors.lastname: Tugwell
authors.affiliation: Department of Economics, University of Göttingen, Göttingen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Bommer
authors.affiliation: Department of Economics, University of Göttingen, Göttingen, Germany.
authors.forename: Cara
authors.initials: C
authors.lastname: Ebert
authors.affiliation: Instituto de Saúde Coletiva, Federal University of Bahia, Salvador, Brazil; National Institute in Science, Technology and Innovation in Health (CITECS), Salvador, Brazil.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Barreto
authors.affiliation: International Initiative for Impact Evaluation, London, UK; International Initiative for Impact Evaluation, Washington DC, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Djimeu
authors.affiliation: Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, USA.
authors.forename: Noah
authors.initials: N
authors.lastname: Haber
authors.affiliation: International Initiative for Impact Evaluation, London, UK; International Initiative for Impact Evaluation, Washington DC, USA.
authors.forename: Hugh
authors.initials: H
authors.lastname: Waddington
authors.affiliation: Center for Global Health and Development, Boston University, Boston, USA.
authors.forename: Peter
authors.initials: P
authors.lastname: Rockers
authors.affiliation: Institute for Fiscal Studies, London, UK.
authors.forename: Barbara
authors.initials: B
authors.lastname: Sianesi
authors.affiliation: School of Public Health, Boston University, Boston, USA.
authors.forename: Jacob
authors.initials: J
authors.lastname: Bor
authors.affiliation: Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, USA.
authors.forename: Günther
authors.initials: G
authors.lastname: Fink
authors.affiliation: College of Education and Human Development, University of Louisville, Louisville, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Valentine
authors.affiliation: Impact Evaluation, World Bank, Washington DC, USA.
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Tanner
authors.affiliation: Hendrix College, Conway, AR, USA.
authors.forename: Tom
authors.initials: T
authors.lastname: Stanley
authors.affiliation: Centre for Medicine and Society, Freiburg University, Freiburg, Germany.
authors.forename: Eduardo
authors.initials: E
authors.lastname: Sierra
authors.affiliation: Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, USA.
authors.forename: Eric Tchetgen
authors.initials: ET
authors.lastname: Tchetgen
authors.affiliation: Department of Global Health and Population, Harvard T.H. Chan School of Public Health, Boston, USA.
authors.forename: Rifat
authors.initials: R
authors.lastname: Atun
authors.affiliation: Department of Economics, University of Göttingen, Göttingen, Germany.
authors.forename: Sebastian
authors.initials: S
authors.lastname: Vollmer
mesh_terms: D006801:Humans; D065228:Non-Randomized Controlled Trials as Topic / Q000379:methods* / Q000706:statistics & numerical data*; D012107:Research Design / Q000706:statistics & numerical data