LEAST COST FORMULATIONS, LTD.
824 Timberlake Drive, Virginia Beach, VA 23464-3239
Tel: (757) 467-0954 Fax: (757) 467-2947
E-mail:
URL:
/
TECHNICAL REPORT
NUMBER:
TR322
DATE: 2012 July 8
TITLE:
Statistical analysis of interlaboratory studies. XXXV. Reproducibility estimates
from proficiency test data.
AUTHOR:
R. A. LaBudde
ABSTRACT: The issue of estimating reproducibility effects from proficiency test (‘PT’) data is
discussed. It is recommended that such data may be used to estimate
reproducibility when: 1) There are sufficient collaborators (8 or more remain in
the final set of data); 2) Collaborator results are removed only for known cause
based on subject-matter expertise and facts. It is recommended that the method
used to estimate reproducibility effects is by the standard deviation of mean
(across replicates, if any) results for the entire dataset net of crude errors with
known causes, corrected for replication. If useful, a lower bound on
reproducibility may be obtained conveniently via the interquartile range of the
original dataset.
KEYWORDS:
1) PT
2) REPRODUCIBILITY 3) VARIANCE
4) ROBUST 5) OUTLIER
6) IQR
REL.DOC.:
REVISED:
Copyright 2012 by Least Cost Formulations, Ltd.
All Rights Reserved
Recommended to OMB by Committee on Statistics: 07-17-2013
Reviewed and approved by OMB: 07-18-2013
1
32
