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An Improved Equation for TBS and ADD : Establishing a Reliable Postmortem Interval Framework for Casework and Experimental Studies
Author(s) -
Moffatt Colin,
Simmons Tal,
LynchAird Jeanne
Publication year - 2016
Publication title -
journal of forensic sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.715
H-Index - 96
eISSN - 1556-4029
pISSN - 0022-1198
DOI - 10.1111/1556-4029.12931
Subject(s) - interval (graph theory) , confidence interval , rounding , scale (ratio) , computer science , statistics , regression analysis , time of death , data mining , medicine , mathematics , medical emergency , cartography , geography , combinatorics , operating system
Megyesi et al.'s ( J Forensic Sci , 2005, 50, 618) paper was important to forensic anthropology as it introduced a quantitative framework for estimating time since death in human cadavers, based upon physical appearance by way of scoring on a novel scale. However, errors concerning rounding, temperature scale, and incorrect use of a statistical regression model render their predictive formula unusable. Based upon only their more reliable data, a more appropriate regression model to predict accumulated degree days ( ADD ) from total body score ( TBS ) is presented. The new model is also a superior fit ( r 2 = 0.91) and produces markedly narrower confidence intervals than the original, which also allowed impossible, negative ADD values. Explanations of the shortcomings in the original analysis and calculations are presented, which it is hoped will help forensic scientists avoid making similar mistakes.