Statistics

Su Mo Tu We Th Fr Sa
30 31 1 2 3 4 5
6 7 8 9 10 11 12
13 14 15 16 17 18 19
20 21 22 23 24 25 26
27 28 29 30 1 2 3
Date/Time:Monday, 14 Nov 2011 from 4:10 pm to 5:00 pm
Location:3105 Snedecor
Cost:Free
URL:www.stat.iastate.edu
Contact:Jeanette La Grange
Phone:515-294-3440
Channel:College of Liberal Arts and Sciences
Categories:Lectures
Actions:Download iCal/vCal | Email Reminder
"Spatial Scan Statistics with Overdispersion," Tongling Zhang, Department of Statistics, Purdue U, W. Lafayette, Indiana

The spatial scan statistic has been widely used in spatial disease surveillance and spatial cluster detection for more than a decade. However, overdispersion often presents in real-world data, causing not only violation of the Poisson assumption but also excessive type I errors or false alarms. In order to account for overdispersion, we extend the Poisson-based spatial scan test to a quasi-Poisson-based test. The simulation shows that the proposed method can substantially reduce type I error probabilities in the presence of overdispersion. In a case study of infant mortality in Jiangxi, China, both tests detect a cluster; however, a secondary cluster is identified by only the Poisson-based test. It is recommended that a cluster detected by the Poisson-based scan test should be interpreted with caution when it is not confirmed by the quasi-Poisson-based test.