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Lookup NU author(s): Professor Fiona Matthews
This work is licensed under a Creative Commons Attribution-NonCommercial 4.0 International License (CC BY-NC 4.0).
Many medical (and ecological) processes involve the change of shape, whereby one trajectory changes into another trajectory at a specific time point. There has been little investigation into the study design needed to investigate these models. We consider the class of fixed effect change-point models with an underlying shape comprised two joined linear segments, also known as broken-stick models. We extend this model to include two sub-groups with different trajectories at the change-point, a change and no change class, and also include a missingness model to account for individuals with incomplete follow-up. Through a simulation study, we consider the relationship of sample size to the estimates of the underlying shape, the existence of a change-point, and the classification-error of sub-group labels. We use a Bayesian framework to account for the missing labels, and the analysis of each simulation is performed using standard Markov chain Monte Carlo techniques. Our simulation study is inspired by cognitive decline as measured by the Mini-Mental State Examination, where our extended model is appropriate due to the commonly observed mixture of individuals within studies who do or do not exhibit accelerated decline. We find that even for studies of modest size (n = 500, with 50 individuals observed past the change-point) in the fixed effect setting, a change-point can be detected and reliably estimated across a range of observation-errors.
Author(s): White SR, Muniz-Terrera G, Matthews FE
Publication type: Article
Publication status: Published
Journal: Statistical Methods in Medical Research
Print publication date: 01/05/2018
Online publication date: 08/08/2016
Acceptance date: 04/06/2016
Date deposited: 19/10/2016
ISSN (print): 0962-2802
ISSN (electronic): 1477-0334
Publisher: Sage Publications Ltd.
PubMed id: 27507286
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