Table of Areas beneath Normal Curve
This is a standard table about the area found under (beneath) a Normal curve at various points along that curve.
This is a standard table about the area found under (beneath) a Normal curve at various points along that curve.
Basic Method Validation ISBN13: 9781886958258 Authors: Nils Person, PhD 
Basic Method Validation,

Basic Method Validation is part of a trilogy of “back to basics” books that focus on analytical quality management. The other two books are Basic QC Practices and Basic Planning for Quality. When I teach these materials, I start with method validation because it introduces the basic concepts of analytical performance and the experimental and statistical techniques needed to describe performance in quantitative terms. These concepts carry through into the practice of QC and the selection of optimal QC procedures via quality design and planning.
The original source of this approach to method validation goes back thirty years to a series of papers that were published in the American Journal of Medical Technology and later as a monograph titled Method Evaluation. My coauthors were Diane J de Vos, Marian R. Hunt, Else F. Quam, R. Neill Carey, and Carl C. Garber, all of whom worked at the University of Wisconsin. We introduced this approach at workshops that were taught at the national ASMT and AACC meetings. Today Neill and Carl, together with David Koch, continue to teach this approach at the AACC national meeting. They now hold the record for the longest running workshop in AACC history.
For more than fifty years, I have worked on quality control and method validation. While statistics, equations and calculations may not change, the context and the environment are constantly evolving. I hope this latest edition helps you understand these method validation numbers in the proper context of your laboratory.James O. Westgard
Madison Wisconsin
 “If regression analysis is used for statistical evaluation of the data, supply slopes and intercepts (and their standard deviations) and standard deviations of residuals (Sy/x, often called standard errors of estimates). Unbiased (e.g., Deming) regression is typically required… The correlation coefficient has limited utility. Residuals plots (e.g., BlandAltman) are often useful. On the horizontal axis, plot the mean of results by the two studied methods, not the result of one method.”
Another alternate regression procedure is called PassingBablock regression, after the authors who described the technique. The slopes are calculated for every combination of two points in the data set, then the slopes are ordered and ranked, and the median value is selected as the best estimate. There is no need for additional information about the relative SDs of the test and comparative methods, thus PassingBablock might be more generally applicable than Deming regression. However, Stockl, Dewitte, and Thienpont seem to recommend Deming regression over PassingBablock regression in a study of comparative regression statistics. The special calculations needed for PassingBablock are not usually found in general purpose statistical packages, so a specialized program is needed.
This is by no means an exhaustive list, but reflects computer programs we know are available at the time of publication:
• Analyseit addon for MicroSoft Excel spreadsheet, available from Analyseit Software, Ltd (http://www.analyseit.com)
• CBStat from Kristian Linnet (http://www.cbstat.com)
• EP Evaluator from David G. Rhoads Associates (http://www.drghoads.com).
• Method Validator from Philippe Marquis at Marquissoft (http://www.marquissoft.com)
This is an Normalized OPSpecs chart with 50% AQA (analytical quality assurance) and with N=2 (2 control measurements).
This is an Normalized OPSpecs chart with 50% AQA (analytical quality assurance) and with N=2 (2 control measurements).