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Accession Number N20120012589
Title Use of Crow-AMSAA Plots to Assess Mishap Trends.
Publication Date Aug 2011
Media Count 7p
Personal Author J. W. Dawson
Abstract Crow-AMSAA (CA) plots are used to model reliability growth. Use of CA plots has expanded into other areas, such as tracking events of interest to management, maintenance problems, and safety mishaps. Safety mishaps can often be successfully modeled using a Poisson probability distribution. CA plots show a Poisson process in log-log space. If the safety mishaps are a stable homogenous Poisson process, a linear fit to the points in a CA plot will have a slope of one. Slopes of greater than one indicate a nonhomogenous Poisson process, with increasing occurrence. Slopes of less than one indicate a nonhomogenous Poisson process, with decreasing occurrence. Changes in slope, known as 'cusps' indicate a change in process, which could be an improvement or a degradation. After presenting the CA conceptual framework, examples are given of trending slips, trips and falls, and ergonomic incidents at NASA (from Agency-level data). Crow-AMSAA plotting is a robust tool for trending safety mishaps that can provide insight into safety performance over time.
Keywords Goodness of fit
Human factors engineering
Human-computer interface
Poisson density functions
Probability theory
Reliability analysis
Safety management
Sensorimotor performance
Systems analysis

Source Agency National Aeronautics and Space Administration
NTIS Subject Category 95E - Life Support Systems
95D - Human Factors Engineering
Corporate Author National Aeronautics and Space Administration, Cleveland, OH. NASA John H. Glenn Research Center at Lewis Field.
Document Type Conference proceedings
Title Note N/A
NTIS Issue Number 1303
Contract Number N/A

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