One of the greatest challenges related to the use of piecewise exponential models (PEMs) is to find an adequate grid of time-points needed in its construction. In general, the number of intervals in such a grid and the position of their endpoints are ad-hoc choices. We extend previous works by introducing a full Bayesian approach for the piecewise exponential model in which the grid of time-points (and, consequently, the endpoints and the number of intervals) is random. We estimate the failure rates using the proposed procedure and compare the results with the non-parametric piecewise exponential estimates. Estimates for the survival function using the most probable partition are compared with the Kaplan-Meier estimators (KMEs). A sensitivity analysis for the proposed model is provided considering different prior specifications for the failure rates and for the grid. We also evaluate the effect of different percentage of censoring observations in the estimates. An application to a real data set is also provided. We notice that the posteriors are strongly influenced by prior specifications, mainly for the failure rates parameters. Thus, the priors must be fairly built, say, really disclosing the expert prior opinion.
Download full-text PDF |
Source |
|---|---|
| http://dx.doi.org/10.1007/s10985-008-9086-0 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Lattice thermal conductivity and phonon properties of polycrystalline graphene.
Nanoscale Adv
December 2024
Department of Mechanical Engineering, IIT Bombay Mumbai Maharashtra India 400076
Using the spectral energy density method, we predict the phonon scattering mean lifetimes of polycrystalline graphene (PC-G) having polycrystallinity only along the -axis with seven different misorientation (tilt) angles at room temperature. Contrary to other studies on PC-G samples, our results indicate a strong dependence of the thermal conductivity (TC) on the tilt angles which we attribute to careful preparation of our grain boundaries-based samples without introducing any local strains and ensuring periodic boundary conditions for the supercells along the and axes. We also show that the square of the group velocity components along and axes and the phonon lifetimes are uncorrelated and the phonon density of states are almost the same for all samples with different tilt angles.
View Article and Find Full Text PDFInequities in Physical Therapy Receipt of US Service Members and Veterans with Low Back Pain.
Arch Phys Med Rehabil
December 2024
Department of Anesthesiology, Uniformed Services University, Bethesda, MD, USA. Electronic address:
Objective: To investigate inequities in time-to physical therapy for patients with low back pain.
Design: Retrospective observational study utilizing data from the Department of Defense and Veterans Health Administration clinical and administrative data repositories derived from medical records, claims, and enrollment data.
Setting: Military Health System, Veterans Health System, and civilian healthcare facilities.
Optimal PaO2 is 130-160 mmHg in the first week for sepsis patients in ICU: a retrospective cohort study based on MIMIC-IV database.
Shock
December 2024
Department of Emergency and Critical Care Medicine, Lianyungang Clinical College of Nanjing Medical University, Lianyungang 222000, Jiangsu, China.
Background: The relationship between the partial pressure of oxygen in arterial blood (PaO2) and the prognosis of sepsis patients, and its potential variation over time, remains unclear. The optimal PaO2 range for sepsis patients has always been a contentious issue, with no consensus. We aimed to explore the association between different levels of PaO2 exposure over time and the 28-day mortality of sepsis patients, and to identify the optimal PaO2 range for sepsis patients within a specific time frame.
View Article and Find Full Text PDFTime to Take a Chance: The Promise of Royston-Parmar Proportional Hazard Models for Understanding Caseload Transitions.
Eval Rev
December 2024
Division of Family Development, New Jersey Department of Human Services, Trenton, NJ, USA.
In this letter to the editor, we compare six different event history models to estimate eligible families participated in a subsidized rental housing program and . Answering these questions can inform efforts to improve program marketing and outreach, staffing and budgeting, triage, bias identification, as well as benchmarking and evaluation. One of six specifications clearly outperforms the others and understanding how will inform similar research pursuits.
View Article and Find Full Text PDFA class of semiparametric models for bivariate survival data.
Lifetime Data Anal
December 2024
Statistics Department, Exact Sciences Institute, Federal University of Minas Gerais, Belo Horizonte, Brazil.
We propose a new class of bivariate survival models based on the family of Archimedean copulas with margins modeled by the Yang and Prentice (YP) model. The Ali-Mikhail-Haq (AMH), Clayton, Frank, Gumbel-Hougaard (GH), and Joe copulas are employed to accommodate the dependency among marginal distributions. Baseline distributions are modeled semiparametrically by the Piecewise Exponential (PE) distribution and the Bernstein polynomials (BP).
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!