Biomedical subjects

S A Hogg

Publications and source records attributed to S A Hogg.

5 recordsLinked to original sources

PubMed1989

GENCOV: a Fortran program that generates randomly censored survival data with covariates.

We present a Fortran program for simulating censored survival data with covariates under the assumption of random censoring. The program generates times distributed according to the uniform distribution, the generalized Gamma distribution, the log-normal distribution and Pettitt's generalized logistic distribution with Box-Cox transformation of the time variable. Covariates can be introduced in the definition of the survival time, resulting in the generalized log-gamma, log-normal and Pettitt's regression models. Thereby the program provides the means for generating censored survival data according to parametric versions of three common regression models for censored survival data: the Accelerated Failure Time, the Proportional Hazards and the Proportional Odds models.

Computer Simulation↗

PubMed1985

GFREG: a computer program for maximum likelihood regression using the Generalized F distribution.

A FORTRAN program is described for maximum likelihood estimation within the Generalized F family of distributions. It can be used to estimate regression parameters in a log-linear model for censored survival times with covariates, for which the error distribution may have a great variety of shapes, including most distributions of current use in biostatistics. The optimization is performed by an algorithm based on the generalized reduced gradient method. A stepwise variable search algorithm for covariate selection is included in the program. Output features include: model selection criteria, standard errors of parameter estimates, quantile and survival rates with their standard errors, residuals and several plots. An example based on data from Princess Margaret Hospital, Toronto, is discussed to illustrate the program's capabilities.

Biometry↗

PubMedDate not supplied

Regression analysis of censored survival data with the generalized F family--an alternative to the proportional hazards model.

We show that the generalized F family is a useful tool for regression analysis with censored survival data. We discuss maximum likelihood estimation and give asymptotic procedures for calculating confidence intervals, tests of significance for the parameters, life expectancy, quantiles and survival rates. Survival data on 704 ovarian carcinoma patients serve to demonstrate the utility of the model.

Adult↗

PubMedDate not supplied

RECPAM: a computer program for recursive partition and amalgamation for censored survival data and other situations frequently occurring in biostatistics. I. Methods and program features.

The methodology of recursive partition and amalgamation in biostatistics is presented and a FORTRAN program for its implementation, RECPAM, is described. RECPAM can be used to obtain classifications of patients according to several criteria commonly occurring in clinical biostatistics: an example is prognostic classification based on survival data. Classes are defined by simple statements, expressed in clinical terms, about predictor variables (e.g. prognostic factors). Special features of RECPAM are: the possibility of implementing a variety of classification criteria, the integration of recursive partition and amalgamation, and the availability of several strategies for constructing classification trees. A simple example to illustrate input and output features is given. The scope and flexibility of RECPAM will be illustrated in greater detail in a subsequent paper.

Algorithms↗

PubMedDate not supplied

The problem-solving curriculum evaluation and development model.

Evaluation has been a feature of nurse education programmes for many years, yet many nurse educators are still struggling with inappropriate, time-consuming procedures, that yield little reward. This paper describes an evaluation and development model that is in the process of implementation at The Royal Free Hospital and Friern School of Nursing. The model has generated much interest from other schools of nursing, and has so far proved easy to use, flexible in application to any course, and has turned evaluation into a purposeful, fruitful, enjoyable and rewarding process.

Curriculum↗