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A critical look at prospective surveillance using a scan statistic
Author(s) -
Correa Thais R.,
Assunção Renato M.,
Costa Marcelo A.
Publication year - 2014
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/sim.6400
Subject(s) - scan statistic , statistic , context (archaeology) , computer science , statistics , signal (programming language) , interval (graph theory) , data mining , mathematics , history , archaeology , combinatorics , programming language
The scan statistic is a very popular surveillance technique for purely spatial, purely temporal, and spatial‐temporal disease data. It was extended to the prospective surveillance case, and it has been applied quite extensively in this situation. When the usual signal rules, as those implemented in SaTScan TM (Boston, MA, USA) software, are used, we show that the scan statistic method is not appropriate for the prospective case. The reason is that it does not adjust properly for the sequential and repeated tests carried out during the surveillance. We demonstrate that the nominal significance level α is not meaningful and there is no relationship between α and the recurrence interval or the average run length (ARL). In some cases, the ARL may be equal to ∞ , which makes the method ineffective. This lack of control of the type‐I error probability and of the ARL leads us to strongly oppose the use of the scan statistic with the usual signal rules in the prospective context. Copyright © 2014 John Wiley & Sons, Ltd.