LABORATORY PROFICIENCY TESTING PROGRAM - REPORT NO 4 GLASS EXAMINATION

• NCJ Number: 47525
• Author(s): ANON
• Date Published: 1975
• Length: 37 pages
• Grant Number(s): 78-NI-99-0048
• Sponsoring Agency: US Dept of Justice; US Dept of Justice NIJ Pub
• Corporate Author: Forensic Sciences Foundation Press
• Sale Source: National Institute of Justice/
• Publication Type: Statistics
• Language: English
• Country: United States of America

Annotation

ANALYSES OF TEST SAMPLES OF GLASS PERFORMED IN 124 FORENSIC LABORATORIES ARE DOCUMENTED IN THE FOURTH OF A SERIES OF LABORATORY PROFICIENCY TESTS.

Abstract

TWO GLASS SAMPLES WERE SENT TO 234 LABORATORIES (SOME RESPONDED THAT THEY DID NOT DO GLASS ANALYSIS, AND SOME SENT NO RESPONSE), TOGETHER WITH THE EXPLANATION THAT ONE SAMPLE HAD BEEN TAKEN FROM THE SCENE OF A BURGLARY AND THE OTHER HAD BEEN TAKEN FROM THE TROUSERS OF A SUSPECT. THE LABORATORIES WERE ASKED TO DETERMINE WHETHER THE ITEMS COULD HAVE A COMMON ORIGIN AND TO EXPLAIN THE METHODS USED IN ARRIVING AT A CONCLUSION. OF THE 124 RESPONDING LABORATORIES, 118 CORRECTLY REPORTED THAT THE TWO SAMPLES COULD NOT HAVE A COMMON ORIGIN, AND 4 WERE INCONCLUSIVE. THE MOST COMMON METHODS OF ANALYSIS USED BY THE LABORATORIES WERE MEASUREMENTS OF DIFFERENCES IN REFRACTIVE INDEX AND DENSITY. THE SURVEY RESULT ARE REPORTED IN NINE TABLES, INCLUDING ITEM-BY-ITEM BREAKDOWNS OF RESPONSES FROM INDIVIDUAL LABORATORIES. THE RESULTS ARE NOT INTERPRETED. AN EXPLANATION OF SURVEY METHODS AND A COPY OF THE QUESTIONNAIRE ARE INCLUDED. OTHER LABORATORY PROFICIENCY TESTS ARE DOCUMENTED IN NCJ 47522-47524 AND 47526-47542. (LKM) DOCUMENTED IN NCJ47522-47524 AND 47526-47542. (LKM)