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Data Gallery: Michelle Schantz SRM 1946: Lake Superior Fish Tissue (k-Lab Consensus Value)

Introduction The accurate measurement of biological species is essential for the timely detection of environmental pollution. Michelle Schantz of CSTL's Analystical Chemistry Division plays a key role in providing industry with a wide assortment of SRM's for the calibration of scientific and industrial devices to carry out such pollution monitoring.

One of Schantz's class of reference materials is SRM 1946: the certification of Lake Superior Fish Tissue. This single SRM does in fact provide certified values for a large number (100) of fatty acids in such fish. The data below is for one such fatty acid: stearic. The stearic concentrations come from a variety of labs (8 in this case) and the final certified value is calculated by arriving at a consensus value across such labs.

The statistical categorization of this problem is the "k-Lab Consensus Mean". This is identical in structure to the Zarr example. A good discussion of this problem is in Mark Levenson's (et al) paper (2000): An ISO GUM Approach to Combining Results from Multiple Methods", Journal of Research of the National Institute of Standards and Technology, 105, 571.

You may also download the Schantz data.

Data

Schantz SRM 1946: Lake Superior Fish Tissue Interlab Consensus Mean Data

Prior Distribution 1:
Non-Informative
(~ Classical)

Zarr Non-informative Prior Distribution

Prior Distribution 2:
Uniform[.30,.36]
 

Zarr Uniform Prior Distribution

Prior Distribution 3:
Normal(.32,.02)
 

Zarr Normal Prior Distribution

Posterior Distribution 1

Posterior Distribution from Non-informative Prior

Posterior Distribution 2

Posterior Distribution from Uniform Prior

Posterior Distribution 3

Posterior Distribution from Normal Prior

Posterior Statistics 1

Posterior Statistics from Non-informative Prior

Posterior Statistics 2

Posterior Statistics from Uniform Prior

Posterior Statistics 3

Posterior Statistics from Normal Prior

Date created: 9/21/2001
Last updated: 9/21/2001
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