METHODS article
Front. Appl. Math. Stat.
Sec. Statistics and Probability
Volume 11 - 2025 | doi: 10.3389/fams.2025.1650059
This article is part of the Research TopicQuantitative Insights into New Cancer Therapies: A Mathematical Modeling ApproachView all articles
Estimating and Testing Blip Effects of Treatments in Sequence via Standardised Point Effects of Treatments
Provisionally accepted
- 1Xiamen University, Xiamen, China
- 2Suntar Research Institute, Singapore, Singapore, Singapore
- 3Karolinska Institutet, Stockholm, Sweden
- 4Department of Humanities, Faculty of Education and Business Studies, University of Gävle, Gävle, Sweden
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Abstract: In longitudinal studies, treatments are often assigned in the form of a sequence to achieve a certain outcome of interest. The blip effect of treatment in sequence is the net effect of treatment on the outcome. In this article, we introduce a method of estimating and testing the blip effects via the standardized point effects of treatments in sequence. Firstly, we apply available methods to estimate the point effects referring to single-point treatments. Then we standardize the point effects to a small number of strata of relevance to the blip effects of interest. Finally, we use the standardized point effects to estimate and test the blip effects. Our method addresses two issues in complex longitudinal studies, a dimension reduction without strict treatment assignment conditions and a targeted analysis of the blip effects of interest across times. The simulation study shows that our method achieves unbiased estimates of the blip effect, maintains nominal coverage probability, and demonstrates high power for the hypothesis testing. A medical example illustrates the application of our method in observational studies.
Keywords: Blip effect, targeted causal inference, point effect, standardized point effect, Structural nested mean model
Received: 19 Jun 2025; Accepted: 15 Sep 2025.
Copyright: © 2025 Liao, Lan, Yin and Wang. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
* Correspondence: Xiaoqin Wang, xwg@hig.se
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