Date: Thu, 11 Nov 1999 14:54:44 EST
From: [email protected]
To: Greg Gogates
Subject: Re: Calibration vs verification

In a message dated 11/10/99 12:08:20 PM Pacific Standard Time,

>After the interesting and stimulating debate recently around the
understanding of calibration, I thought I would try my luck with requesting
viewpoints regarding the difference between calibration and verification.
This topic was only briefly mentioned during the calibration debate.
>
>I have a calibration background and therefore tend to treat calibration as
the measurement process whereby the result is a known value of some
parameter whereas verification is usually comparing that known value
against some specification/perfomance limit to check compliance.
>
>I am led to believe however that this terminology has a very different
meaning in chemical and other test laboratories where it would seem
verification is the process by which the performance of an analysis/test
system can be checked for satisfactory performance before testing a sample.
>
>I would be keen to hear from the group an all possible interpretations and
meanings of these terms. I am due to present a paper at a forthcoming
metrology calibration and testing workshop early in 2000 and wish to avoid
too much "calibration" bias.
>
>Kind Regards
>Eddie
> >>
Eddie,

The following is an official list of definitions. It may be of some help in your talk. It seems to me there is no clear distinction among many of the terms. For example, testing, and perhaps calibration, appear to be subsets of inspection.

Ralph

measurement uncertainty - parameter, associated with the result of a measurement, that characterizes the dispersion of the values that could reasonably be attributed to the measurand . (International Vocabulary of Basic and General Terms in Metrology)

calibration - a set of operations that establish, under specified conditions, the relationship between values of quantities indicated by a measuring instrument or measuring system or values represented by a material measure or a reference material, and the corresponding values realized by the standard.

NOTES

1 The result of a calibration permits either the assignment of values or measurands to the indications or the determination of corrections with respect to indications.

2 A calibration may also determine other metrological properties such as the effect of influence quantities.

3 The result of a calibration may be recorded in a document sometimes called a calibration certificate or a calibration report. (International Vocabulary of Basic and General Terms in Metrology)

test - technical operation that consists of the determination of one or more characteristics of a given product, process or service according to a specified procedure. (ISO Guide 2: 1991)

inspection - evaluation for conformity by measuring, observing, testing or gauging the relevant characteristics (ISO/IE /guide 2)

inspection - activity such as measuring, examining, testing or gauging one or more characteristics of an entity and comparing the results with specified requirements in order to establish whether conformity is achieved for each characteristic. (ISO Standard 8402)

certification - procedure by which a third party gives written assurance that a product, process or service conforms to specified requirements. (ISO Standard 8402)

verification - conformation by examination and provision of objective evidence that specified requirements have been fulfilled. (ISO Standard 8402)