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Statistical Evaluation of Calibration Check Intervals

NCJ Number
Canadian Society of Forensic Science Journal Volume: 44 Issue: 2 Dated: June 2011 Pages: 41-46
Michael Rosland; Ronald Pon
Date Published
June 2011
6 pages
This study examined whether changing the length of the calibration check intervals for approved alcohol screening devices would affect the devices' ability to provide stable readings.
In 2009 the Alcohol Test Committee of the Canadian Society of Forensic Science changed the calibration check interval of Approved Screening Devices from every 2 weeks to every 31 days. Data from calibration checks of a group of Alco-sensor IV DWF screening devices were analyzed using a contingency table and x2 analysis as well as a significant test for differences in proportions. There were no statistically significant differences between the length of time of the calibrating interval and the frequency of a device requiring recalibration. This analysis shows the Alco-Sensor IV DWF is no more likely to require calibration up to and including a 5 week interval when compared to a 2 week interval, supporting the Alcohol Test Committee decision. (Published Abstract)