A critical look at prospective surveillance using a scan statistic.
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Date
2015
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Abstract
The scan statistic is a very popular surveillance technique for purely spatial, purely temporal, and spatialtemporal
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 SaTScanTM( 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 notmeaningful 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.
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Keywords
Average run length, Recurrence interval, Scan statistic
Citation
CORREA, T. R.; ASSUNÇÃO, R. M.; COSTA, M. A. A critical look at prospective surveillance using a scan statistic. Statistics in Medicine, v. 34, p. 1081-1093, 2015. Disponível em: <http://onlinelibrary.wiley.com/doi/10.1002/sim.6400/epdf>. Acesso em: 15 fev. 2017.