(I have only CC'ed to AI-GEOSTATS, not being subscribed to the other lists)
On Mon, 22 Oct 2001 [EMAIL PROTECTED] wrote: > Hi everyone, > > In Singapore, we define a dengue cluster (referring to an outbreak when > dengue fever is spreading contagiously from one person to the next) as at > least 2 cases (points) within 200 m of each other and within 3 weeks of > incidence of each other. With about 2,000 cases so far this year, I have > about about 80 clusters according to this definition. > > However, I suspect that the occurence of some clusters (especially the ones > with just 2 or 3 cases) may be by chance, instead of an actual disease > transmission happening. How can I test this? Possibly, a Monte Carlo > simulation of some kind will help. Is there any software out there that can > help to do this? SATScan has got some promising functions, unfortunately it > deals with areal or polygon data and not point data (I think). > One possibility are the stkhat family of functions in Splancs, including stmctest - a Monte-Carlo test of space-time clustering, see: Diggle, P., Chetwynd, A., Haggkvist, R. and Morris, S. 1995 Second-order analysis of space-time clustering. Statistical Methods in Medical Research, 4, 124-136. Software to run this in R (www.r-project.org) is contributed as a package to be found on the same site (maintained by me), in S-PLUS at the original site: http://www.maths.lancs.ac.uk/~rowlings/Splancs/. The article is not very easy to get at, a further short description can be found in: Bailey, T. C. and Gatrell, A. C. 1995, Interactive spatial data analysis. Longman, Harlow, pp. 122-125. A student from Thailand (Wutjanun Muttitanon <[EMAIL PROTECTED]>) also drew my attention to an article I think using stkhat: Exploratory space-time analysis of reported dengue cases during an outbreak in Florida,Puerto Rico,1991-1992 Author : Amy C.Morrison and et al. Journal : American Tropical Hygine ,Vol 58(3) pp287-298. If you follow up this route using the splancs package for R, I'd be very grateful for feedback to help improve its documentation and functionality. Roger -- Roger Bivand Economic Geography Section, Department of Economics, Norwegian School of Economics and Business Administration, Breiviksveien 40, N-5045 Bergen, Norway. voice: +47 55 95 93 55; fax +47 55 95 93 93 e-mail: [EMAIL PROTECTED] and: Department of Geography and Regional Development, University of Gdansk, al. Mar. J. Pilsudskiego 46, PL-81 378 Gdynia, Poland. -- * To post a message to the list, send it to [EMAIL PROTECTED] * As a general service to the users, please remember to post a summary of any useful responses to your questions. * To unsubscribe, send an email to [EMAIL PROTECTED] with no subject and "unsubscribe ai-geostats" followed by "end" on the next line in the message body. DO NOT SEND Subscribe/Unsubscribe requests to the list * Support to the list is provided at http://www.ai-geostats.org
