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Search Publications by: Blaza Toman (Assoc)

Displaying 101 - 125 of 173

CCQM K80 Comparison of value-assigned CRMs and PT materials: creatinine in human serum

February 19, 2013

Author(s)

Johanna Camara, David L. Duewer, Hugo H. Gasca-Aragon, Katrice Lippa, Blaza Toman

Final report of key comparison CCM.P-K12 for very low helium flow rates (leak rates)

January 1, 2013

Author(s)

James A. Fedchak, Blaza Toman, Karl Jousten

Quantitative leak tests with vacuum technology have become an important tool in industry for safety and operational reasons and to meet environmental regulations. In lack of a relevant key comparison, so far, there are no calibration measurement

Comparison of value-assigned CRMs and PT materials: experimental design and data evaluation

August 22, 2012

Author(s)

David L. Duewer, Hugo H. Gasca-Aragon, Katrice A. Lippa, Blaza Toman

This document provides the tedious mathematical details for OAWG Track B Key Comparisons that is, this document presents and discusses the statistical approaches involved in the design of Track B studies and analysis of the resulting data. This

Experimental Design and Data Evaluation Considerations for Comparisons of Higher-Order Value-Assigned Materials

August 22, 2012

Author(s)

David L. Duewer, Hugo H. Gasca-Aragon, Katrice A. Lippa, Blaza Toman

The analysis of higher-order value-assigned materials (HOVAMs) such as certified reference materials (CRMs) and value-assigned proficiency testing materials can help assess the equivalence of chemical measurement processes. When two or more such materials

Alternative Analyses of Measurements of the Planck Constant

July 5, 2012

Author(s)

Blaza Toman

We compare different methods for the adjustment of the Planck constant using recent, inconsistent data. First we discuss the popular Birge ratio method. By stating the underlying statistical model we critically assess and modify this method. We then

An international assessment of the metrological equivalence of higher-order measurement services for creatinine in serum

April 2, 2012

Author(s)

Johanna Camara, Katrice A. Lippa, David L. Duewer, Hugo H. Gasca-Aragon, Blaza Toman

Background: The CCQM-K80 Key Comparison directly assessed the equivalence of many of the worlds higher-order value-assigned materials (HOVAMs) for creatinine in human serum. This 2009 international study compared the certified values and uncertainties of

A Bayesian Approach to the Evaluation of Comparisons of Individually Value-Assigned Reference Materials

March 3, 2012

Author(s)

Blaza Toman

A new data analysis procedure is presented for the evaluation of comparisons of reference materials individually prepared and value-assigned by different organizations to measurements made in a single laboratory under repeatability measurements. The

Estimation and Uncertainty analysis of Dose Response in an inter-laboratory experiment

November 13, 2011

Author(s)

Blaza Toman, Elijah J. Petersen, John T. Elliott

An inter-laboratory experiment for the evaluation of toxic effects of NH2-polystyrene nanoparticles on living cells was performed with five participating laboratories. Previously published results in the field of nano toxicology have been contradictory

Tutorial for Metrologists on the Probabilistic and Statistical Apparatus Underlying the GUM and Related Documents

November 9, 2011

Author(s)

Antonio M. Possolo, Blaza Toman

A review and précis of the meaning and calculus of probability, including random variables, probability distributions, functions of random variables, and of Bayesian statistical inference, with many illustrative examples.

Bayesian Uncertainty Analysis for a Regression Model Versus Application of GUM Supplement 1 to the Least-Squares Estimate

May 5, 2011

Author(s)

Blaza Toman, Clemens Elster

Application of least-squares as, for instance, in curve fitting is an important tool of data analysis in metrology. It is tempting to employ the supplement 1 to the GUM (GUM-S1) to evaluate the uncertainty associated with the resulting parameter estimates

Quantifying Model Error

February 11, 2011

Author(s)

Kevin B. McGrattan, Blaza Toman

A methodology is proposed for reporting the results of fire model validation studies that consist mainly of comparisons of model predictions and experimental measurements. The difference between the two is a combination of model error and experimental

Analysis of key comparisons: Estimating laboratories biases by a fixed effects model using Bayesian Model Averaging

March 11, 2010

Author(s)

Blaza Toman, Clemens Elster

We propose a novel procedure for the analysis of key comparison data. The goal of the procedure is to detect biases in the reported measurement results which are not accounted for by quoted uncertainties. A fixed effects bias model is employed which

Laboratory Effects Models for Interlaboratory Comparisons

June 16, 2009

Author(s)

Blaza Toman, Antonio M. Possolo

Statistical analysis of inter-laboratory comparisons (e.g. Key Comparisons, Supplemental Comparisons) is required to produce an estimate of the measurand called a reference value and further, measures of equivalence of the participating laboratories