What is ratio or reciprocity-type measurements in ISO15189

[jelly1921]

Hi everyone!

Could anyone give me example(s) what is ratio or reciprocity-type measurements in 5.6.3 of ISO 15189?

5.6.3 A programme for calibration of measuring systems and verification of trueness shall be designed and performed so as to ensure that results are traceable to SI units or by reference to a natural constant or other stated reference. Where none of these are possible or relevant, other means for providing confidence in the results shall be applied, including but not limited to the following:
a) participation in a suitable programme of interlaboratory comparisons;
b) use of suitable reference materials, certified to indicate the characterisation of the material;
c) examination or calibration by another procedure;
d) ratio or reciprocity-type measurements;
e) mutual consent standards or methods which are clearly established, specified, characterized and mutually agreed upon by all parties concerned;
f) documentation of statements regarding reagents, procedures or the examination system when traceability is provided by the supplier or manufacturer.

Thanks advance

Jelly

[Ajit Basrur]

Does anyone has an answer to Jelly1921's question ?

[Mr Niceguy]

Originally Posted by jelly1921

Hi everyone!

Could anyone give me example(s) what is ratio or reciprocity-type measurements in 5.6.3 of ISO 15189?

5.6.3 A programme for calibration of measuring systems and verification of trueness shall be designed and performed so as to ensure that results are traceable to SI units or by reference to a natural constant or other stated reference. Where none of these are possible or relevant, other means for providing confidence in the results shall be applied, including but not limited to the following:
a) participation in a suitable programme of interlaboratory comparisons;
b) use of suitable reference materials, certified to indicate the characterisation of the material;
c) examination or calibration by another procedure;
d) ratio or reciprocity-type measurements;
e) mutual consent standards or methods which are clearly established, specified, characterized and mutually agreed upon by all parties concerned;
f) documentation of statements regarding reagents, procedures or the examination system when traceability is provided by the supplier or manufacturer.

Thanks advance

Jelly

In my opinion it is just another way of stating the requirement (b). Compare the unknown quantity with response from known reference material/artefact. This phraseology seems to come from ANSI/NCSL Z-540-199,the US interpretation of ISO 25. ISO 17025 does not have it.