ISSN:0277-6715    

DOI:10.1002/sim.4780120302

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

年代:1993

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780120303

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

年代:1993

数据来源: WILEY

ISSN:0277-6715    

DOI:10.1002/sim.4780120304

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

年代:1993

数据来源: WILEY

摘要:

AbstractIntervention and prevention strategies for the U.S.A. for the year 2000 have been broadly defined into 22 priority areas encompassing 332 health objectives. NCHS and its data systems have the major responsibility for providing the data for half of these objectives and assisting in a wide array of other data programmes both within and outside of CDC. This paper describes the process used to arrive at these objectives, highlights a few of them, and presents four examples of objectives NCHS is engaged in tracking: breast cancer mortality, breast examinations, infant mortality and cholesterol levels.

ISSN:0277-6715    

DOI:10.1002/sim.4780120305

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

年代:1993

数据来源: WILEY

摘要:

AbstractWe evaluate sexual behaviour change among homosexual men enrolled in the cohorts in four AIDS Community Demonstration Projects. Behaviour change is classified following the stages of behaviour change model and described using a Markov model. Predictors of behaviour change are identified and evaluated using logit models for correlated data. Sexual behaviour change within the cohort could be modelled as a first‐order Markov process. In addition, predictors suggested by models of health behaviour were correlated with particular patterns of sexual behaviour change. Our evaluation revealed a variety of patterns of sexual behaviour change in the cohorts and suggests multi‐faceted interventions for promotion of behaviour cha

ISSN:0277-6715    

DOI:10.1002/sim.4780120306

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn January, February and March of 1989 an epidemic of rubeola occurred on the campus of Texas Tech University. A vaccination programme was initiated as soon as the epidemic was confirmed. Extensive case histories of all confirmed cases were collected by the Lubbock City Health Department and given an exhaustive statistical analysis by a group from the Department of Mathematics at Texas Tech University. The data and statistical analysis were used to formulate stochastic and deterministic models of the measles epidemic based on the standard SEIR model. The analysis and the simulations indicate that in order to prevent a measles outbreak on a university campus a high rate of immunity may be required (>98 per cent). The assumptions in the models raise some interesting questions regarding social contacts which require further investigation.

ISSN:0277-6715    

DOI:10.1002/sim.4780120307

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

年代:1993

数据来源: WILEY

摘要:

AbstractBivariate survival analysis models that incorporate random effects or ‘frailty’ provide a useful framework for determining the effectiveness of interventions. These models are based on the notion that two paired survival times are correlated because they share a common unobserved value of a random variate from a frailty distribution. In some applications, however, investigators may have some information that characterizes pairs and thus provides information about their frailty. Alternatively, there may be an interest in assessing whether the correlation within certain types of pairs is different from the correlation within other types of pairs. In this paper, we present a method to incorporate ‘pair‐wise’ covariate information into the dependence parameter of the bivariate survival function.We provide an example using data from the Framingham Heart Study to investigate the times until the occurrence of two events within an individual: the first detection of hypertension and the first cardiovascular disease event. We model the dependence between these two events as a function of the age of the individual at the time of enrolment into the Framing

ISSN:0277-6715    

DOI:10.1002/sim.4780120308

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

年代:1993

数据来源: WILEY

摘要:

AbstractA good measure of field vaccine efficacy should evaluate the direct protective effect of vaccination on the person who receives the vaccine. The conventional estimator for vaccine efficacy depends on population level factors that are either unrelated or indirectly related to the direct biological action of the vaccine on persons, including population structure, duration of the study, the fraction vaccinated, and herd immunity, that is, indirect effects. Indirect effects can cause the conventional vaccine efficacy estimator to be inaccurate. We review alternative vaccine efficacy estimators that control for indirect effects at the population level. Thus, they are more accurate than the conventional estimator. We use epidemic simulations to explore the robustness of the conventional and proposed estimators under different field conditions. In addition, we apply the different vaccine efficacy estimators to data from a measles epidemic in Muyinga, Burundi.

ISSN:0277-6715    

DOI:10.1002/sim.4780120309

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

年代:1993

数据来源: WILEY

摘要:

AbstractContinuous time autoregressive (CAR(1)) and random walk models of time series data are provided for detecting non‐random shifts and trends of tumour markers in breast cancer patients following resection for cure. The continuous time random walk model with observation error is extended to the case of multiple patient time series. These models can be used to monitor large numbers of patients with time series with few sampling events that are serially correlated and unequally spaced. Further, the methodologies can be used to recommend appropriate testing intervals. A Kalman filter recursive algorithm is used to calculate the likelihood functions arising from the CAR(1) and random walk models and to calculate recursive residuals, which are monitored by Shewhart—cusum sche

ISSN:0277-6715    

DOI:10.1002/sim.4780120310

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

年代:1993

数据来源: WILEY

摘要:

AbstractPoor response rates, perhaps as low as 10 to 30 per cent, certainly bring into question the validity of any survey suffering such a malady. Repeated mailouts are capable of providing information on those persons who are resistant to responding. If one is willing to assume an exponential drop‐off in response rates, then imputation is possible for the entire group of non‐responders. Furthermore, a second exponential drop‐off in favourable (or non‐favourable) responses to particular items within the questionnaire leads to closed form estimates of population parameters and their associated standard errors. Three or more mailouts also provide a test of validity of the model

ISSN:0277-6715    

DOI:10.1002/sim.4780120311

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

年代:1993

数据来源: WILEY