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Diagnosing Physical Abuse Using Bayes' Theorem: A Preliminary Study

NCJ Number
173323
Journal
Child Abuse Review Volume: 7 Issue: 3 Dated: May-June 1998 Pages: 178-188
Author(s)
A M Kemp; K W Kemp; R Evans; L Murray; Z E S Guildea; F D J Dunstan; J R Sibert
Date Published
1998
Length
11 pages
Annotation
This British study compared the patterns of bruises in a physically abused group of children and a control group, investigated whether these could be modeled statistically to enable probabilities of typical bruise patterns to be calculated, and applied Bayes' Theorem to find the probability that a child with a given bruise pattern has been the subject of physical abuse.
Abstract
The physically abused group consisted of 75 children, aged 0-14 years, who were seen by the medical child protection service for South Glamorgan. A control group of 289 children consisted of those who presented to the Accident and Emergency Department at the Cardiff Royal Infirmary after an accidental injury. Findings show that the bruise distribution in physically abused and control children was well described by a negative binomial distribution. There was a different distribution for the three different regions of the body in physically abused children. The bruising frequency and distribution for the physically abused group was different from that of the controls. The study was able to use parameters derived from these distributions to calculate posterior probabilities of physical abuse given a particular pattern of bruises using Bayes' Theorem. The study thus shows that Bayes' Theorem can be used to combine prior probabilities of physical abuse with observed patterns of bruising in given children to obtain posterior probabilities of abuse. This principle has considerable potential for better diagnosis of the physically abused child. 2 tables and 13 references