摘要:

In 1979, two of the eight municipal wells servicing Woburn, Massachusetts, were discovered to be contaminated with several chlorinated organics. Shortly afterwards, the town was found to have an elevated rate of childhood leukemia. Using recent information about the space—time distribution of water from the two contaminated wells, we find positive statistical associations between access to this water and the incidence rates of childhood leukemia, perinatal deaths (1970–1982), two of five categories of congenital anomalies, and two of nine categories of childhood disorders. We find no associations with spontaneous abortions, low birth weight, or the other categories of congenital anomalies and childhood disorders. This article discussed these results and other features of the data relevant to their interpretation.

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478307

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478308

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478309

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478310

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478311

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478312

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478313

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

The hazard function of time-related events, such as death or reoperation following heart valve replacement, often is time-varying in a structured fashion, as is the influence of risk factors associated with the events. A completely parametric system is presented for the decomposition of time-varying patterns of risk into additive, overlapping phases, descriptively labeled as early, constant-hazard, and late. Each phase is shaped by a different generic function of time constituting a family of nested equations and is scaled by a separate logit-linear or log-linear function of concomitant information. Model building uses maximum likelihood estimation. The resulting parametric equations permit hazard function, survivorship function, and probability estimates and their confidence limits to be portrayed and adjusted for concomitant information. These provide a comprehensive analysis of time-related events from which inferences may be drawn to improve, for example, the management of patients with valvar heart disease.

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478314

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

Spatial data modeled to have come from a random function with a nonstationary mean are considered. The spatial prediction method known as kriging exploits second-order spatial correlation structure to obtain minimum variance predictions of certain average values of the random function. But to do so, it must be assumed that either the mean function (the drift) is known up to a constant or the second-order structure (the variogram) is known exactly. Knowledge of the drift allows the (stationary) variogram to be estimated and leads to ordinary kriging. Knowledge of the variogram allows the drift to be estimated and leads to universal kriging. More usually, neither is known. This article shows how median polish of gridded spatial data provides a resistant and relatively bias-free way of kriging in the presence of drift, yet yields results as good as the mathematically optimal (but operationally difficult) universal kriging. Comparisons are performed on two data sets.

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478315

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor

摘要:

To develop a model to estimate the degree of unobserved heterogeneity in morality risks in a population, it is necessary to specify two types of functions, one describing the age-specific rate of increase of mortality risks for individuals and the other describing the distribution of mortality risks across individuals. There has been considerable interest in the question of how sensitive the estimates of heterogeneity are to the choices of these functions. To explore this question, high-quality data were obtained from published Medicare mortality rates for the period 1968–1978 for analysis of total mortality among the aged. In addition, national vital statistics data for the period 1950–1977 were used to analyze adult lung cancer mortality. For these data, the estimates of structural parameters were less sensitive to reasonable choices of the heterogeneity distribution (gamma vs. inverse Gaussian) than to reasonable choices of the hazard rate function (Gompertz vs. Weibull).

ISSN:0162-1459    

DOI:10.1080/01621459.1986.10478316

出版商:Taylor & Francis Group    

年代:1986

数据来源: Taylor