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NCJRS Abstract

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NCJ Number: 149587 Find in a Library
Title: TWGDAM (Technical Working Group on DNA Analysis Methods) Consensus Approach for Applying the "Ceiling Principle" To Derive Conservative Estimates of DNA Profile Frequencies
Journal: Crime Laboratory Digest  Volume:21  Issue:2  Dated:(April 1994)  Pages:21- 27
Corporate Author: Technical Working Group on DNA Analysis Methods
United States of America
Date Published: 1994
Page Count: 7
Sponsoring Agency: National Institute of Justice/
Rockville, MD 20849
NCJRS Photocopy Services
Rockville, MD 20849-6000
Technical Working Group on DNA Analysis Methods
Quantico, VA
Sale Source: National Institute of Justice/
NCJRS paper reproduction
Box 6000, Dept F
Rockville, MD 20849
United States of America

NCJRS Photocopy Services
Box 6000
Rockville, MD 20849-6000
United States of America
Document: PDF
Type: Report (Technical)
Format: Article
Language: English
Country: United States of America
Annotation: This report of the Technical Working Group on DNA Analysis Methods (TWGDAM) critiques the National Research Council's recommendation that the "ceiling principle" be used to calculate DNA profile frequency estimates and describes the techniques recommended by the TWGDAM, the "fixed-bin ceiling" approach and the "floating-bin ceiling" approach.
Abstract: The "ceiling principle", devised by the National Research Council, provides an even more conservative estimate of the likelihood of occurrence of a DNA profile than the fixed-bin or floating-bin methods currently used by the forensic community. The TWGDAM does not recommended the ceiling principle because its use is based on the faulty premise that there is more genetic variation among subgroups within a major population group than between major population groups. Extant data demonstrate the opposite conclusion and that the application of the ceiling principle is unnecessary. Methods currently used by forensic scientists have been shown to be robust scientifically. For those courts that still prefer DNA profile frequency estimates based on the conservative interim ceiling principle approach, TWGDAM has developed a consensus approach for the ceiling principle. There are two basic approaches to establishing ceiling principle frequencies. These are based on using either fixed or floating bins to assign allele frequencies. Since both the fixed-bin and floating-bin ceiling principle approaches, which are described in this article, yield similar DNA profile frequency estimates, either can be used. It is unnecessary to provide estimates for both approaches. The choice is up to the laboratory. 36 references
Main Term(s): Science and Technology
Index Term(s): DNA fingerprinting; Police policies and procedures; Testing and measurement
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