ArticleBMC medical research methodology2025
Interpretation of coefficients in segmented regression for interrupted time series analyses.
Article in BMC medical research methodology, 2025. The graph could read no effect estimate from its abstract, so it casts no vote on the map. Cited by 2 papers.
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Who cites it
2 citing papers in PubMed.
- Receipt of postpartum diabetes screening after gestational diabetes mellitus in the United States, 2016-2022.Diabetic medicine : a journal of the British Diabetic Association · 2026Article
- Contract architecture and time-to-first public activation of robotic urology programs in Poland: a nationwide open-data linkage study.Journal of robotic surgery · 2026Article
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6 authors.
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Abstract
backgroundSegmented regression, a common model for interrupted time series (ITS) analysis, primarily utilizes two equation parametrizations. Interpretations of coefficients vary between the two segmented regression parametrizations, leading to occasional user misinterpretations.
methodsTo illustrate differences in coefficient interpretation between two common parametrizations of segmented regression in ITS analysis, we derived analytical results and present an illustration evaluating the impact of a smoking regulation policy in Italy using a publicly accessible dataset. Estimated coefficients and their standard errors were obtained using two commonly used parametrizations for segmented regression with continuous outcomes. We clarified coefficient interpretations and intervention effect calculations.
resultsOur investigation revealed that both parametrizations represent the same model. However, due to differences in parametrization, the immediate effect of the intervention is estimated differently under the two approaches. The key difference lies in the interpretation of the coefficient related to the binary indicator for intervention implementation, impacting the calculation of the immediate effect.
conclusionsTwo common parametrizations of segmented regression represent the same model but have different interpretations of a key coefficient. Researchers employing either parametrization should exercise caution when interpreting coefficients and calculating intervention effects.
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