Material Measurement Laboratory

Applied Chemicals and Materials Division

Thermodynamics Research Center

Director of NIST (1994), Dr. John W. Lyons, wrote,

“It is generally agreed that the usefulness of measurement results ….is to a large extent determined by the quality of the

statements of uncertainty that accompany them.”

(From Technical Note 1297; 1994)

Material Measurement Laboratory

Applied Chemicals and Materials Division

Thermodynamics Research Center

GDC: data point

Data point

Properties

State variables

Expanded uncertainty

Expanded combined uncertainty

Expanded uncertainty

Material Measurement Laboratory

Applied Chemicals and Materials Division

Thermodynamics Research Center

Derivation of combined uncertainty

Data point

Expanded uncertainty of property

Expanded combined uncertainty

Expanded uncertainties of statevariables

Derivatives bystate variables

Material Measurement Laboratory

Applied Chemicals and Materials Division

Thermodynamics Research Center

Sources of information

Repeatability

Device specification

Calibration/Comparison

CalcUncertainty function

Method/Device Method specifications

Scattering/deviations

Uncertainty

Literature source TRC GDC software

Expert judgment(quality factor)

Material Measurement Laboratory

Applied Chemicals and Materials Division

Thermodynamics Research Center

Uncertainty specification form

Material Measurement Laboratory

Applied Chemicals and Materials Division

Thermodynamics Research Center

Uncertainty calculation