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DETECTION OF OVERALL SPACE–TIME CLUSTERING IN A NON-UNIFORMLY DISTRIBUTED POPULATION

✍ Scribed by JUKKA RANTA; JANNE PITKÄNIEMI; MARJATTA KARVONEN; ESA VIRTALA; JARMO RUSANEN; ALFRED COLPAERT; ARVO NAUKKARINEN; JAAKKO TUOMILEHTO

Publisher
John Wiley and Sons
Year
1996
Tongue
English
Weight
800 KB
Volume
15
Category
Article
ISSN
0277-6715

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✦ Synopsis

We developed a test statistic based on an approach of Whittemore et a / . (1987) to detect space-time clustering for non-infectious diseases. We extended the spatial test of Whittemore et al. by deriving conditional probabilities for Poisson distributed random variables. To combine spatial and time distances we defined a distance matrix D, where d,j is the distance between the ith andjth cell in a three-dimensional space-time grid. Spatial and temporal components are controlled by a weight. By altering the weight, both marginal tests and the intermediate test can be reached. Allowing a continuum from a pure spatial to a pure temporal test, the best result will be gained by trying different weights, because the occurrence of a disease might show some temporal and some spatial tendency to cluster. We examined the behaviour of the test statistic by simulating different distributions for cases and the population. The test was applied to the incidence data of insulin-dependent diabetes mellitus in Finland. This test could be used in the analysis of data which are localized according to map co-ordinates, by addresses or postcodes. This information is important when using the Geographical Information System (CIS) technology to compute the pairwise distances needed for the proposed test.

📜 SIMILAR VOLUMES

Letter: Detection of overall space-time
Letter: Detection of overall space-time clustering in a non-uniformly distributed population by Jukka Ranta, J. Pitkäniemi, M. Karvonen, E. Virtala, J. Rusanen, A. Colpaert, A. Naukkarinen and J. Tuomilehto, Statistics in Medicine, 15, 2561–2572 (1996)
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Ranta et al. propose a test for space-time clustering by generalizing Whittemore et al.'s test. However, I think this test is inappropriate judging by several important points discussed below.

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