Deriving Objective Probability of Detection for Missing-Person Search: Validating Use of Effective Sweep Width and Associated Mathematical Models

Kenneth B. Chiacchia, PhD
Heather E. Houlahan, AB
Mountaineer Area Rescue Group
Appalachian Search and Rescue Conference
Morgantown, WV


Effective sweep width (W) promises objective probability of detection (POD) values for guiding missing-person search efforts. However, methods for measuring W produce large uncertainties. Also, models for
generating POD from W have not been validated for ground-based search. The authors applied least-square fits of POD data collected in the field for air-scent dog teams as well as human searchers using
the two most prevalent models to derive W values. The method routinely fits the data to an R-square of .8 with more statistical power than previous methods, and appears to be detector-agnostic. The authors
present recommendations for optimizing its use in the field.

KEYWORDS: SAR, effective sweep width, probability of detection, search theory, dogs, smell

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