title: The estimation of branching curves in the presence of subject-specific random effects.
abstract: Branching curves are a technique for modeling curves that change trajectory at a change (branching) point. Currently, the estimation framework is limited to independent data, and smoothing splines are used for estimation. This article aims to extend the branching curve framework to the longitudinal data setting where the branching point varies by subject. If the branching point is modeled as a random effect, then the longitudinal branching curve framework is a semiparametric nonlinear mixed effects model. Given existing issues with using random effects within a smoothing spline, we express the model as a B-spline based semiparametric nonlinear mixed effects model. Simple, clever smoothness constraints are enforced on the B-splines at the change point. The method is applied to Women's Health data where we model the shape of the labor curve (cervical dilation measured longitudinally) before and after treatment with oxytocin (a labor stimulant).
authors.affiliation: Department of Epidemiology and Biostatistics, The Milken Institute School of Public Health at the George Washington University, Washington, DC, 20052, U.S.A.
authors.forename: Angelo
authors.initials: A
authors.lastname: Elmi
authors.forename: Sarah J
authors.initials: SJ
authors.lastname: Ratcliffe
authors.forename: Wensheng
authors.initials: W
authors.lastname: Guo
mesh_terms: D001699:Biometry / Q000379:methods*; D003198:Computer Simulation; D003627:Data Interpretation, Statistical; D005260:Female; D006801:Humans; D007747:Labor Stage, First / Q000187:drug effects* / Q000502:physiology; D008137:Longitudinal Studies; D015233:Models, Statistical; D010120:Oxytocics / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D010121:Oxytocin / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D011247:Pregnancy; D012044:Regression Analysis; D013997:Time Factors; D016064:Vaginal Birth after Cesarean / Q000379:methods / Q000706:statistics & numerical data*
chemical_list: D010120:Oxytocics; D010121:Oxytocin
keywords: branching curves; curve registration; mixed effects models