OMB Meeting Book - January 8, 2015

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LEAST COST FORMULATIONS, LTD. 824 Timberlake Drive, Virginia Beach, VA 23464-3239 Tel: (757) 467-0954 Fax: (757) 467-2947 E-mail: office@lcftld.com URL: http://lcfltd.com/

TECHNICAL REPORT

NUMBER:

TR323

DATE: 2012 August 13

TITLE:

Statistical analysis of interlaboratory studies. XXXVI. When robust statistics make sense in proficiency test studies.

AUTHOR: R. A. LaBudde ABSTRACT: The use of ‘robust’ statistical estimators for measures of central location and variation are discussed. Robust estimators for measures of central location are non-controversial and acceptable. Robust estimators for measures of variation, such as reproducibility standard deviation, are heavily biased and therefore deprecated. Examples of performance of robust estimators are given for four example distributions (normal, lognormal, student-t and gamma).

KEYWORDS:

1) PT

2) REPRODUCIBILITY 3) VARIANCE

4) ROBUST 5) OUTLIER

6) IQR

REL.DOC.:

TR322

REVISED:

Copyright 2012 by Least Cost Formulations, Ltd. All Rights Reserved

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Recommended to OMB by Committee on Statistics: 07-17-2013 Reviewed and approved by OMB: 07-18-2013