Summary Unexplained heterogeneity in univariate survival data and association multivariate can both be modelled by the inclusion of frailty effects. This paper investigates consequences ignoring analysis, fitting misspecified Cox proportional hazards models to marginal distributions. Regression coefficients are biased towards 0 an amount which depends magnitude on variability terms form distribution. The bias is reduced when censoring present. Fitted curves also differ substantially from...

A one-dimensional random walk is studied in which, at each stage, the probabilities of continuing same direction or changing are p and 1 – , respectively. Exact expressions derived for n -step transition probabilities, various limiting distributions investigated.

We consider optimal dynamic treatment regime determination in practice. Model building, checking, and comparison have had little or no attention so far this literature. Motivated by an application on dosage of anticoagulants, we propose a modeling estimation strategy that incorporates the regret functions Murphy (2003, Journal Royal Statistical Society, Series B 65, 331-366) into regression model for observed responses. Estimation is quick diagnostics are available, meaning variety candidate...

Doctors' survival predictions for terminally ill patients have been shown to be inaccurate and there has an argument less guesswork more use of carefully constructed statistical indices. As statisticians, the authors are confident in predictive value models indices individual times. This paper discusses illustrates a variety measures which can used summarise information available from model. The argue that useful at group or population level, but human is so uncertain even best analysis...

In this article we combine ideas from spatial statistics with lifetime data analysis techniques to investigate possible variation in survival of adult acute myeloid leukemia patients northwest England. Exploratory suggests both clinically and statistically significant rates across the region. A multivariate gamma frailty model incorporating dependence is proposed applied, results confirming hazard on location.

Summary The problem of analysing longitudinal data that are complicated by possibly informative drop-out has received considerable attention in the statistical literature. Most researchers have concentrated on either methodology or application, but we begin this paper arguing more could be given to study objectives and relevant targets for inference. Next summarize a variety approaches been suggested dealing with drop-out. A long-standing concern subject area is all methods require...

Summary Random effects or shared parameter models are commonly advocated for the analysis of combined repeated measurement and event history data, including dropout from longitudinal trials. Their use in practical applications has generally been limited by computational cost complexity, meaning that only simple special cases can be fitted using readily available software. We propose a new approach exploits recent distributional results extended skew normal family to allow exact likelihood...

Diabetic retinopathy is a complication of diabetes that produces changes in the blood vessel structure retina, which can cause severe vision problems and even blindness. In this paper, we demonstrate by identifying topological features very high resolution retinal images, construct classifier discriminates between healthy patients those with diabetic using summary statistics these features. Topological data analysis identifies as connected components holes images describes extent to they...

Journal Article A serially correlated gamma frailty model for longitudinal count data Get access Robin Henderson, Henderson Search other works by this author on: Oxford Academic Google Scholar Silvia Shimakura Biometrika, Volume 90, Issue 2, June 2003, Pages 355–366, https://doi.org/10.1093/biomet/90.2.355 Published: 01 2003

The goal of relative survival methodology is to compare the experience a cohort with that background population. Most often an additive excess hazard model employed, which assumes each person's sum 2 components—the population obtained from life tables and attributable specific condition. Usually covariate effects on are assumed have proportional hazards structure parametrically modelled baseline. In this paper, we introduce new fitting procedure using expectation–maximization algorithm,...

Methods for the combined analysis of survival time and longitudinal biomarker data have been developed in recent years, with most emphasis on modelling estimation. This paper focuses use marker trajectories as individual-level surrogates survival. A score test association which requires only standard methods implementation is derived initial identification candidate biomarkers. assessing efficacy markers are discussed a measure contrasting conditional marginal distributions proposed. An...

Journal Article Morphology of the Structural Root System Sitka Spruce 1. Analysis and Quantitative Description Get access R. HENDERSON, HENDERSON +Department Statistics, University EdinburghMayfield Road, Edinburgh, EH9 3JZ° Present address: Department Newcastle-upon-TyneNewcastle-upon-Type, NE1 7RU Search for other works by this author on: Oxford Academic Google Scholar E. D. FORD, FORD *Institute Terrestrial EcologyBush Estate, Penicuik, Midlothian, EH26 0QB RENSHAW, RENSHAW 3JZ J. DEANS...

SUMMARY 1. Foot-and-mouth disease broke out on three pig farms of the Spetchley area Worcestershire after virus had been carried to them in skimmed milk. 2. A study natural features and climatic conditions during outbreak show that wind could have from one or other these twenty-six others total thirty-two infected. 3. Bringing cattle fields keeping their sheds offered no protection. Nine farmers did so but only effect was onset infection delayed for a day so. 4. The direction which cow-sheds...

Summary Relative survival techniques are used to compare experience in a study cohort with that expected if background population rates apply. The especially useful when cause-specific death information is not accurate or available as they provide measure of excess mortality group patients certain disease. Whereas these methods based on comparisons, we present here transformation approach which instead gives for each individual an outcome relative the appropriate population. new easily...

Journal Article A problem with the likelihood ratio test for a change-point hazard rate model Get access ROBIN HENDERSON Department of Mathematics and Statistics, University Newcastle-upon-TyneNewcastle upon Tyne NE1 7RU, U.K. Search other works by this author on: Oxford Academic Google Scholar Biometrika, Volume 77, Issue 4, December 1990, Pages 835–843, https://doi.org/10.1093/biomet/77.4.835 Published: 01 1990 history Received: November 1989 Revision received: July

Abstract A complication of long‐term anticoagulation is that the optimal dose level varies not only between patients but over time within patients, in response to short‐term changes lifestyle. Consequently, doseage needs be adaptive there are as yet no accepted decision rules. Since anticoagulant use increasing worldwide a need for more objective and routine procedures. In this paper, we describe an analysis observational longitudinal data, aimed at determining reactive dose‐changing...

Additive regression models are preferred over multiplicative in the analysis of relative survival data. Such preferences mainly grounded practical experience with mostly cancer registries data, where basic assumption additivity hazards is more likely to be met. Also, interpretation coefficients meaningful additive than models. Nonetheless, question goodness fit assumed model must still addressed, and while there an abundance methods check models, respective arsenal for almost empty. We...