ISSN:0277-6715    

DOI:10.1002/sim.4780121902

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.4780121903

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

年代:1993

数据来源: WILEY

摘要:

AbstractClassical tests for clustering rarely have a major role in the investigation of disease clusters at the neighbourhood level performed by a health department. When examining a single cluster, the boundaries are often ill‐defined, and the dimension )geographic, occupational, iatrogenic( is rarely obvious. Furthermore, using cluster tests to routinely scan disease registries looking for clusters is undesirable for several reasons. A better approach is to be vigilant for unusual environmental exposures, and to evaluate the impact they may have. In this context, cluster techniques may serve as part of a larger investigation that includes other epidemiologic approache

ISSN:0277-6715    

DOI:10.1002/sim.4780121904

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

年代:1993

数据来源: WILEY

摘要:

AbstractDozens of methods have been proposed for the identification of disease clusters, although only a few are used routinely in published investigations. New methods, although designed to exploit some particular aspect of the data or use some specific statistical tool, are rarely compared thoroughly in terms of power or performance. Users, when confronted with the multitude of methods available, often select methods arbitrarily, basing choices on software availability, ease of implementation, or use experience rather than considerations of statistical power, possible alternative hypotheses )that is, cluster structure( and likely confounding. In this review, we extend our typology of disease clustering methods and apply it to many of the extant methods identifying strengths, weaknesses and unique features of the methods. We conclude with recommendations for which methods should be applied to which types of situations.

ISSN:0277-6715    

DOI:10.1002/sim.4780121905

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

年代:1993

数据来源: WILEY

摘要:

AbstractThis paper presents combinatorial )exact( methods that are useful in the analysis of disease cluster data obtained from small environments, such as buildings and neighbourhoods. Maxwell–Boltzmann and Fermi–Dirac occupancy models are compared in terms of appropriateness of representation of disease incidence patterns )space and/or time( in these environments. The methods are illustrated by a statistical analysis of the incidence pattern of bone fractures in a setting wherein fracture clustering was alleged to be occurring. One of the methodological results derived in this paper is the exact distribution of the maximum cell frequency in occupancy mod

ISSN:0277-6715    

DOI:10.1002/sim.4780121906

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

年代:1993

数据来源: WILEY

摘要:

AbstractA variable is measured at two locations separated by a given distance. Are the values more similar to each other if the locations are oriented in one direction than another? This question has application to studies of human genetics, epidemics, and acid rain. One obvious analytic approach, regression on latitude and longitude, fails when data are non‐directional )isotropic( but spatially autocorrelated. Moreover, although non‐zero slope implies similarity between neighbours, the converse is not true. IDIFF, a statistic derived from Moran's coefficient of spatial autocorrelation, is developed to detect general directional effects that apply to the collection of data points. Simulations suggest that, when data have isotropic spatial autocorrelation but are incorrectly assumed to be independent, IDIFF will at worst reject too little. IDIFF has good power to distinguish epidemics that spread non‐directionally from those that spread in a favoured dire

ISSN:0277-6715    

DOI:10.1002/sim.4780121907

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

年代:1993

数据来源: WILEY

摘要:

AbstractIn a disease monitoring system embracing several diseases and communities, alarms indicating a significant increase in disease incidence will frequently occur even though the false alarm rate has been set quite low. An approach is presented by which an alarm is determined as either confirmed or rejected according to data observed subsequent to the alarm. The suggested procedure is expected to weed out a substantial proportion )say about 75 per cent( of the false alarms at the expense of some delay in detecting a true alarm.

ISSN:0277-6715    

DOI:10.1002/sim.4780121908

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

年代:1993

数据来源: WILEY

摘要:

AbstractTango proposed an index for detecting disease clustering in time applicable to grouped data obtained from a population that remains fairly stable over the study period. In this paper, we show that Tango's index is a two‐dimensionalU‐statistic having an asymptotic normal distribution. To apply this result in the finite sampling situation, an Edgeworth expansion is used and is shown to be at least as accurate as Tango's best result in approximating the tails of his test statistic under the null hypothesis. This is extended to show that the Edgeworth expansion can be used to approximate the power of Tango's test statistic under selected alternatives to randomness. A power study based on simulations is conducted to compare the power of Tango's index to that of three of its competit

ISSN:0277-6715    

DOI:10.1002/sim.4780121909

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe scan statistic is the maximum number of events in an interval of fixed lengthwas the subinterval moves over the entire time frame. Previous research derived the null distribution of the scan statistic under the conditional model which assumed that the total number of events was fixed, and under the unconditional model which let the total number of events be a random variable. This paper derives approximations for the power of the scan test for a pulse alternative. Under this alternative, the relative risk of disease on a subinterval )τ, τ +w(, τ unknown, is θ‐fold as high as it is for other subintervals of lengthw. Two sets of approximations are given for each model. The first approximation gives highly accurate results, but requires use of a personal computer. The second procedure can be performed on a hand‐held calculator and appears very accurate for the cases e

ISSN:0277-6715    

DOI:10.1002/sim.4780121910

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

年代:1993

数据来源: WILEY

摘要:

AbstractThe scan statistic is used to test the hypothesis that the observed events occur at random )uniformly distributed( in time or space versus the hypothesis that they cluster within a moving window of sizew. To implement the testing procedure based on the scan statistic its tail probabilities have to be effectively evaluated. In this article a survey of results on the approximations of the distribution of the scan statistic and its moments is presented. Numerical results comparing these approximations are also given. Numerous references with applications in epidemiological studies using the scan statistics are mentioned. Related scan statistics that have been used in many other interesting applications are listed in the reference section. The article concludes with the presentation of unsolved problems related to the scan statistic.

ISSN:0277-6715    

DOI:10.1002/sim.4780121911

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

年代:1993

数据来源: WILEY