SED navigation bar go to SED home page go to SED projects page go to NIST home page SED Home Page SED Contacts SED Projects SED Products and Publications Search SED Pages

Data Gallery: Guenther/ISO NOx Calibration (Errors-in-Variables Regression)

Introduction Frank Guenther is head of CSTL's Gas Metrology program in the Analytical Chemistry Division. The NIST Gas Metrology calibration service plays a critical role in the measurement of a wide spectrum of gases worldwide, and is a major player in ISO metrology.

The data analyzed below comes from a Guenther run involving the measurment of nitrous oxides. The calibration problem is complicated by the fact that the horizontal axis also has (non-negligible) noise, and so usual regression techniques do not apply. The statistical classification of this problem is "Errors-in-Variables". To show the flexibility of the Bayesian approach, we focus on the aspect of estimating the slope from the errors-in-variables linear fit. Such slope calculation (along with the intercept calculation) is a necessary intermediate step to the computation of the final calibration values.

You may also download the Guenther data.

Data

Guenther/ISO NOx Calibration Data

Prior Distribution 1:
Non-Informative
(~ Classical)

Guenther/ISO Non-informative Prior Distribution

Prior Distribution 2:
Uniform[.0001,.0003]
 

Guenther/ISO Uniform Prior Distribution

Prior Distribution 3:
Normal(.0002,.00001)
 

Guenther/ISO 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
Please email comments on this WWW page to sedwww@nist.gov.

[ SED Home |  Bayesian Home |  Data Gallery |  Previous |  Next ]