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Using A Quick-Basic Application Based On The DAC Statistic To Detect Spatial Clusters

Authors

  • Alexandru I. Petrisor

    University of South Carolina, Norman J. Arnold School of Public Health, Department of Environmental Health Sciences

  • Liviu Dragomirescu

    University of Bucharest, Faculty of Biology, Department of Systems Ecology

  • J. Wanzer Drane

    University of South Carolina, Norman J. Arnold School of Public Health, Department of Epidemiology and Biostatistics

  • Kirby L. Jackson

    University of South Carolina, Norman J. Arnold School of Public Health, Department of Epidemiology and Biostatistics

  • David J. Cowen

    University of South Carolina, College of Liberal Arts, Department of Geography

DOI:
https://doi.org/10.61416/ceai.v4i1.86
Abstract
Spatial distributions find applications in various fields, such as public health, biology, ecology, geography, economics or sociology. The DAC statistic is the difference between the empirical cumulative distribution of cases and that of non-cases at a particular point. This study uses the longitude and latitude as the coordinates of the homes of mothers in Spartanburg County, SC who gave birth to their babies in 1989 or 1990. A priori, clusters are expected in areas of high population densities, especially considering risk factors for low birthweight. The chosen axes are east-west (x) and north-south (y). From a mathematical perspective the choice is arbitrary. For any size of a random sample of locations taken from the 6434 live births there is a noticeable variation of the location of the DAC statistic with random rotations within a given sample, when transformed back to original longitude and latitude. Simulations indicated that the location of the maximum DAC statistic is not unique, moreover there is a geometrical locus of it, and this varies as the orientation of the axes changes. Therefore, the DAC statistic should be used with caution, but its usefulness as a set of spatial descriptive statistic is not diminished in the least.
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Published
2002-03-31
Issue
Vol. 4 No. 1 (2002)
Section
Articles