Table 4

Refining Historical Limits Method to Improve Disease Cluster Detection, New York City, New York, USA

Alison Levin-Rector¹

, Elisha L. Wilson², Annie D. Fine, and Sharon K. Greene

Author affiliations: New York City Department of Health and Mental Hygiene, Queens, New York, USA

Explanation of signals produced by HLM_original and HLM_refined in the 12 weekly analyses, New York City, New York, USA, May 20–August 5, 2013*

Explanation	No. signals produced by HLM_original	No. signals produced by HLM_refined
Attributable to an uncorrected bias toward signaling
Neighborhood disease count threshold too low	47†	0
Pending cases in current period	21	0
Increasing trends in baseline period	3	0
Total signals attributable to an uncorrected bias toward signaling	71	0
Attributable to the correction of a bias against signaling
Confirmatory proportion higher in current period than in baseline period	9	0
Accounted for data accrual lags	0	17
Deleted outliers in baseline period	0	2
Adjusted for decreasing trends in baseline period	0	1
Total signals attributable to the correction of a bias against signaling	9	20
Not attributable to any known systematic bias	54	54
Total signals	134	74

*HLM, historical limits method; HLM_original, method as originally applied in NYC prior to May 20, 2013; HLM_refined, refined method applied starting May 20, 2013.
†These were excluded from the calculation of type I and type II error rates.

Main Article

¹Current affiliation: RTI International, Research Triangle Park, North Carolina, USA.

²Current affiliation: Colorado Department of Public Health and Environment, Denver, Colorado, USA.

Page created: January 20, 2015

Page updated: January 20, 2015

Page reviewed: January 20, 2015

The conclusions, findings, and opinions expressed by authors contributing to this journal do not necessarily reflect the official position of the U.S. Department of Health and Human Services, the Public Health Service, the Centers for Disease Control and Prevention, or the authors' affiliated institutions. Use of trade names is for identification only and does not imply endorsement by any of the groups named above.