Background: Use of robust and broadly applicable statistical alerting methods is essential for a ... more Background: Use of robust and broadly applicable statistical alerting methods is essential for a public health syndromic surveillance system, such as CDC BioSense program. Methods: Excess visit counts (at least two standard deviations above calculated baseline expectations) were artificially injected into gastrointestinal (GI) syndrome-related daily aggregate time series data from the BioSense Syndromic Surveillance system. Algorithm sensitivity was calculated as the ratio of days with injects for which the algorithm value exceeded a computed threshold. We compared these sensitivities among the three adaptive methods: a CUSUM (CS) chart and two Shewhart chart variations based on sums and ratios (C2a, C2b) adjusted for total visits. We also examined overall sensitivities before and after stratification by weekday versus weekend and holiday with different background ratios to total visits that are GI-related. Results: At a daily background alert rate of 5% and 1%, the sensitivities ra...
Background: Use of robust and broadly applicable statistical alerting methods is essential for a ... more Background: Use of robust and broadly applicable statistical alerting methods is essential for a public health syndromic surveillance system, such as CDC BioSense program. Methods: Excess visit counts (at least two standard deviations above calculated baseline expectations) were artificially injected into gastrointestinal (GI) syndrome-related daily aggregate time series data from the BioSense Syndromic Surveillance system. Algorithm sensitivity was calculated as the ratio of days with injects for which the algorithm value exceeded a computed threshold. We compared these sensitivities among the three adaptive methods: a CUSUM (CS) chart and two Shewhart chart variations based on sums and ratios (C2a, C2b) adjusted for total visits. We also examined overall sensitivities before and after stratification by weekday versus weekend and holiday with different background ratios to total visits that are GI-related. Results: At a daily background alert rate of 5% and 1%, the sensitivities ra...
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Papers by Loren Akaka