Completed Projects
Gamma, Software and Statistics for Uncertain Locations
Geoffrey Jacquez, BioMedware, Inc., PI
This work was supported by grants R43-CA065366 and R44-CA065366 for 1995 and 1997-1998, respectively, from the National Cancer Institute
Research Abstract
We developed software and cluster statistics appropriate when the exact space-time location of health events are known. Health professionals are investigating an increasing number of possible disease clusters, and statistical tests play an important role in cluster description and analysis. Existing cluster statistics assume precise data, when in reality health events are often imprecise (e.g. place-of- residence is known only to the census district or zip-code) and uncertain (e.g. 'I first became ill sometime in 1985'). Most cluster statistics can be written as the cross product of two matrices where one matrix reflects nearest neighbor, distance of adjacency relationships and the second matrix is health related (e.g. case-control identities). This research explored a general approach to clustering which incorporates uncertainty regarding space-time locations into the nearest neighbor, distance or adjacency relationship. Because the approach is general the proposed methods can be used with almost all exiting cluster tests.
In phase 1 we determined feasibility by implementing this general approach for Cuzick & Edwards (nearest neighbor-based), Mantel's (distance-based) and Knox's (adjacency-based) tests. In phase 2 we extended the approach to 10 other cluster tests and evaluated the fuzzy clustering algorithms using statistical power comparisons based on 3 realistic disease simulations.
Patents
The work accomplished in this project led to four patents: "Method of measuring the degree of association using dimensionally-referenced data" 6,360,184 and its continuations 6,460,011, 6,704,686, and 6,738,728.
Publications
Jacquez, G.M., 1999. Spatial statistics when locations are uncertain, Geographic Information Sciences 5: 77-87.
Jacquez, G.M., 1998 GIS as an Enabling Technology In GIS and Health (Eds. T. Gatrell and M. Loytonen), Taylor and Francis, London.
Jacquez, G.M., L.A. Waller. 1996. The effect of uncertain locations on disease cluster statistics. Proceedings of the Second International Symposium on Spatial Accuracy Assessment in Natural Resources and Environmental Sciences May 21-23, 1996, Fort Collins, CO, 259-266.
Jacquez, G.M. 1996 A k-nearest test for space-time interaction. Statistics in Medicine 15: 1935-49.
Jacquez, G.M., 1996. Disease cluster tests for imprecise space-time locations. Statistics in Medicine,15: 873-885.
Jacquez, G.M., R. Grimson, L. Waller, and D. Wartenberg. 1996. The analysis of disease clusters Part 2: Introduction to techniques. Infection Control and Hospital Epidemiology, 17: 385-397.
Jacquez, G.M., L. Waller, R. Grimson, and D. Wartenberg, 1996. The analysis of disease clusters Part 1: State of the art. Infection Control and Hospital Epidemiology, 17: 319-127.