摘要:

AbstractGeographical coherence may be defined as the degree to which the behaviour of a time series in one geographical area corresponds with the time series behaviour in another. This paper illustrates the concept using the epidemiological time series of reported monthly measles morbidity for the states of the United States for the 27 years from January 1962 to December 1988. Over this period, as measles morbidity has declined in response to vaccination campaigns, and as the seasonal peaking of the disease in late spring has become less pronounced, the geographical coherence has altered at the national, divisional, regional and state levels. There was a steady decline in coherence from 1962 to 1980. In 1981, a dramatic reduction occurred, but there has been some recovery since. The implications for spatial forecasting models of these reducing levels of coherence are discussed.

ISSN:0277-6715    

DOI:10.1002/sim.4780111102

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractSeveral methods exist for short term projection of the numbers of AIDS cases. Some use extrapolation of empirical curves fitted to data up to a given time, whereas others such as the popular method of ‘back projection’ or actuarial methods also use information about the process. In this paper we describe a dynamic model based on a distributed modelling technique allowing for variability both in infectiousness and in age distribution of the population at risk. Some model parameters are taken from the literature, others are estimated from AIDS incidence data from the homo/bisexual population in Amsterdam. The model described here simulates prevalence and incidence of HIV infection. We present prediction intervals for two years from January 1990 onwards. We discuss three scenarios based on the estimated model, two of which consider early treatment with anti‐viral drugs. Given the model and the state of the epidemic in Amsterdam, early treatment intervention must be combined with very drastic measures for reducing infectivity in order to have any serious impact on the course of the epi

ISSN:0277-6715    

DOI:10.1002/sim.4780111103

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractEpidemiological studies of disease can make use of ancillary risk‐factors, acquired from individuals outside the disease study. For example, several disease studies might use the same job‐exposure matrix to quantify risks due to occupational exposure to industrial agents. We construct a graphical model to combine a logistic regression disease model with models for the ancillary data and the risk‐factor distribution in the population. We estimate the graphical model using Gibbs sampling, and in simulations compare it with methods of direct substitution into logistic regre

ISSN:0277-6715    

DOI:10.1002/sim.4780111104

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractGraphical methods based on the analysis of differences between log cumulative hazard functions are considered for a two‐group semi‐proportional hazard model which allows for interaction between treatments and covariates. Confidence procedures and test statistics that can be used to test for interaction and for main effects are developed. Their use is illustrated by applying them to the analysis of kidney transplant data from the University of California, San Franci

ISSN:0277-6715    

DOI:10.1002/sim.4780111105

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe study duration in a clinical trial with censored survival data is the sum of the accrual duration, which determines the sample size in a traditional sense, and the follow‐up duration, which more or less controls the number of events to be observed. We propose a design procedure for determining the study duration or for calculating the power in a group sequential clinical trial with censored survival data and possibly unequal patient allocation between treatments, adjusting for stratified randomization. The group sequential method is based on the use function approach. We describe a clinical trial recently activated by the Eastern Cooperative Oncology Group for an illustration of the proposed procedur

ISSN:0277-6715    

DOI:10.1002/sim.4780111106

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractThe needs for statistical surveillance in different areas of medicine are described. The predictive value of an alarm and other measures for the evaluation of alarm procedures are suggested. The measures are used to evaluate some common methods of continual surveillance of time series. It is demonstrated that some methods have about the same properties at the start of the surveillance period as later. This is however not the case for all methods. For some methods the consequence of an early alarm should be quite different from that of a late one.

ISSN:0277-6715    

DOI:10.1002/sim.4780111107

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractA general estimating equation approach is used to obtain estimates of sensitivity and specificity when the data consist of correlated binary outcomes. First order approximations to the variances of estimated sensitivity and specificity for prospective and retrospective studies are given. Data from a dental study are used to motivate and illustrate the methods.

ISSN:0277-6715    

DOI:10.1002/sim.4780111108

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWe propose a new procedure for constructing a confidence interval about the kappa statistic in the case of two raters and a dichotomous outcome. The procedure is based on a chi‐square goodness‐of‐fit test as applied to a model frequently used for clustered binary data. The procedure provides coverage levels that are accurate in samples of smaller size than those required for other procedures. The procedure also has use for significance‐testing and the planning of corresponding sample size requi

ISSN:0277-6715    

DOI:10.1002/sim.4780111109

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

摘要:

AbstractWhen computing the sample size for studies using McNemar's test, one needs to know the probability of discordance and the odds ratio to be detected. In many studies, the investigator is unable to specify the probability of discordance, but can state, at least approximately, the marginal probabilities of each variable. This information leads to restrictions on the possible values of the cell probabilities and provides a range of admissible values for the off‐diagonal cells. We compute the sample size needed in these circumstances and compare them to the results cited by Schlesselman and Connettet al.These sample sizes for the method are quite close to those found in the Monte Carlo study of Connettet a

ISSN:0277-6715    

DOI:10.1002/sim.4780111110

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780111111

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1992

数据来源: WILEY