Background: The number of studies using joint modelling of longitudinal and survival data have increased in the past two decades, but analytical techniques and software shortcomings have remained. A joint model is often used for analysis of a combination of longitudinal sub-model and survival sub-model using shared random effects. Cox regression commonly referring to the survival sub-model, should not be used when proportional hazards assumptions are not satisfied. In such cases, the parametric survival model is preferable.
Methods: We describe different parametric survival models for survival sub-model of joint modelling. We demonstrate how these models can be fit using gsem command (used for generalized structural equation model) in Stata that allows the model to be jointly continuous longitudinal and parametric survival data. With this code, linear mixed effect model is used for the longitudinal sub-model of the joint model, allowing random and fixed effects of the time. In gsem command for survival sub-models, there are five different choices: exponential, Weibull, log-normal, log-logistic and gamma accelerated failure time models.
Results: In this paper, we have described properties of gsem command for parametric joint modelling and have shown an application for parametric joint models on the 312 patients with primary biliary cirrhosis, which is a major health problem in the western world.
Conclusions: We showed how parametric joint models can be used with the gsem command which has been the only Stata code in the literature to fit the parametric joint models, for the generalized structural equation model, and we used the primary biliary cirrhosis dataset for the detailed application of the command. Thus, the gsem command becomes more useful for fitting parametric joint models.
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http://dx.doi.org/10.1016/j.cmpb.2020.105612 | DOI Listing |
Materials (Basel)
January 2025
Department of Mechanical Engineering (CEME), National University of Sciences and Technology (NUST), Sector H-12, Islamabad 46000, Pakistan.
Welding-induced residual stress has the capacity to significantly compromise the integrity of mechanical components. Its minimization therefore plays a critical role in the selection of process parameters during the welding process. Friction stir welding is a useful joining technique to weld many materials that are not amenable to the traditional welding techniques.
View Article and Find Full Text PDFActa Vet Scand
January 2025
Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Grønnegårdsvej 8, Frederiksberg C, DK-1870, Denmark.
Background: Information on indirect contacts (e.g. contact with visitors and non-porcine species on farms, shared staff and equipment, contact with trucks) is often poorly recorded even though it constitutes a risk in terms of disease transmission.
View Article and Find Full Text PDFJ Biomech
January 2025
UNC-NC State Joint Department of Biomedical Engineering, North Carolina State University and University of North Carolina at Chapel Hill, 1407, Engineering Building III, 1840 Entrepreneur Drive, Raleigh, NC 27695, USA. Electronic address:
Continuous relative phase (CRP) quantifies coordination for cyclic motions as the difference in the phase portrait locations between its constituent coordinates and has been widely used in populations with neuromuscular impairments. Continuous analyses, like statistical parameter mapping (SPM), provide greater resolution than traditional techniques that first compress CRP across a section of the cycle to a single point, like mean average relative phase (MARP). However, both analyses neglect the effect of intermediate event timing (e.
View Article and Find Full Text PDFBioengineering (Basel)
January 2025
Biomechanics Laboratory, Division of Sport and Exercise, School of Health and Life Sciences, University of the West of Scotland, Paisley PA1 2BE, UK.
Golfers must modify their motor patterns when the demands of a putting task change. The objective was to compare joint angles and putter kinematics during putting at two distances and inclines. Recreational golfers ( = 14) completed putts over four conditions: 3-foot putts on flat and incline surfaces, and 7-foot putts on flat and incline surfaces.
View Article and Find Full Text PDFBiomed Signal Process Control
August 2024
CNRS-University of Montpellier LIRMM, UMR5506, Interactive Digital Human, Montpellier, France.
Correlation coefficients play a pivotal role in quantifying linear relationships between random variables. Yet, their application to time series data is very challenging due to temporal dependencies. This paper introduces a novel approach to estimate the statistical significance of correlation coefficients in time series data, addressing the limitations of traditional methods based on the concept of effective degrees of freedom (or effective sample size, ESS).
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