PMID- 27091355 OWN - NLM STAT- MEDLINE DCOM- 20170918 LR - 20220310 IS - 1365-2753 (Electronic) IS - 1356-1294 (Linking) VI - 22 IP - 6 DP - 2016 Dec TI - Using machine learning to identify structural breaks in single-group interrupted time series designs. PG - 851-855 LID - 10.1111/jep.12544 [doi] AB - RATIONALE, AIMS AND OBJECTIVES: Single-group interrupted time series analysis (ITSA) is a popular evaluation methodology in which a single unit of observation is being studied, the outcome variable is serially ordered as a time series and the intervention is expected to 'interrupt' the level and/or trend of the time series, subsequent to its introduction. Given that the internal validity of the design rests on the premise that the interruption in the time series is associated with the introduction of the treatment, treatment effects may seem less plausible if a parallel trend already exists in the time series prior to the actual intervention. Thus, sensitivity analyses should focus on detecting structural breaks in the time series before the intervention. METHOD: In this paper, we introduce a machine-learning algorithm called optimal discriminant analysis (ODA) as an approach to determine if structural breaks can be identified in years prior to the initiation of the intervention, using data from California's 1988 voter-initiated Proposition 99 to reduce smoking rates. RESULTS: The ODA analysis indicates that numerous structural breaks occurred prior to the actual initiation of Proposition 99 in 1989, including perfect structural breaks in 1983 and 1985, thereby casting doubt on the validity of treatment effects estimated for the actual intervention when using a single-group ITSA design. CONCLUSIONS: Given the widespread use of ITSA for evaluating observational data and the increasing use of machine-learning techniques in traditional research, we recommend that structural break sensitivity analysis is routinely incorporated in all research using the single-group ITSA design. CI - (c) 2016 John Wiley & Sons, Ltd. FAU - Linden, Ariel AU - Linden A AD - Linden Consulting Group, LLC, Ann Arbor, MI, USA. AD - Division of General Medicine, Medical School, University of Michigan, Ann Arbor, MI, USA. FAU - Yarnold, Paul R AU - Yarnold PR AD - Optimal Data Analysis, LLC, Chicago, IL, USA. LA - eng PT - Journal Article DEP - 20160419 PL - England TA - J Eval Clin Pract JT - Journal of evaluation in clinical practice JID - 9609066 SB - IM MH - Adult MH - Discriminant Analysis MH - Female MH - Humans MH - *Interrupted Time Series Analysis MH - *Machine Learning MH - Male MH - Middle Aged MH - Research Design MH - Selection Bias OTO - NOTNLM OT - causal inference OT - data mining OT - interrupted time series analysis OT - machine learning OT - maximum-accuracy model OT - optimal discriminant analysis OT - quasi-experimental OT - structural breaks EDAT- 2016/04/20 06:00 MHDA- 2017/09/19 06:00 CRDT- 2016/04/20 06:00 PHST- 2016/03/21 00:00 [received] PHST- 2016/03/23 00:00 [accepted] PHST- 2016/04/20 06:00 [pubmed] PHST- 2017/09/19 06:00 [medline] PHST- 2016/04/20 06:00 [entrez] AID - 10.1111/jep.12544 [doi] PST - ppublish SO - J Eval Clin Pract. 2016 Dec;22(6):851-855. doi: 10.1111/jep.12544. Epub 2016 Apr 19.