Degree of equivalence

Program (IMEP) degree of equivalence of the quality of chemical measurements (IMEP 2005) Laboratories from around the world participate... 

In a farsighted move in 1989, the European Union laboratory IRMM started a series of interlaboratory comparisons to provide objective evidence for the degree of equivalence and the quality of chemical measurements by comparing a participant s measurement results with external certified reference values (IRMM 2006). At the time most proficiency testing schemes used consensus results for the mean and standard deviation to derive z scores. With the IMEP-1 analysis of lithium in serum, the world was alerted to the problem of lack of accuracy in analytical measurements. The data of the first IMEP-1 trial are replotted in figure 5.6 notice that the apparent outlier was the only laboratory to come close to the assigned value. 

Comparisons program and is known as degree of equivalence. This consists of the signed difference between the results, with a combined expanded uncertainty. Thus, for two laboratories with results Ux and x2 U2, the degree of equivalence is ( - x2), with expanded uncertainty VU + . A Student s t test with H0 that the results come from a population with degree of equivalence = 0 can then be used to determine if there is a significant difference between the results. 

Fig. 6. Results obtained when measuringthe same measurand by different methods estimating the degree of reproducibility, or the degree of equivalence, is achieved for the participating laboratories, not the establishment of the traceability of each result...

Interlaboratory comparisons of the results of different laboratories are an a posteriori process. They yield another useful product the establishment of the degree of reproducibility of results of different laboratories, or degree of equivalence between the measurement capability of the participating laboratories. 

The IMEP philosophy is to create an awareness of these issues within both the measurement and accreditation communities so that they can take appropriate action themselves. Key to this endeavour is the task of disseminating traceability which can be best described as to deliver Si-traceable reference values carried by real-life samples to interested laboratories in order to enable them to determine the degree of equivalence of their own measurement result and a certified Si-traceable value. ... 

It follows that participation in the IMEP programme (or any other for that matter) does not itself ensure trace-ability of the participant s result. That must be done by the participants themselves each time they perform a measurement. If the traceability of a participant s result has been established to the same common reference (in this case the SI) as the certified Si-traceable value, comparability of the two values has become possible and a degree of equivalence (dependent on the uncertainty ranges) will be a natural consequence of this process. 

To evaluate the degree of equivalence of the national primary measurement procedures for pH, the first key comparison for this quantity was recently carried out by the CCQM on two phosphate buffer solutions. These experiments were piloted by the PTB Germany and involved another ten metrology institutes. A first evaluation of the results obtained shows that the majority of the results agree within the uncertainty stated by the participants. The draft B for this comparison will be available soon. 

Spectroscopic studies are useful in structural investigations because they provide information which is complementary to that derived from diffractometric data. The information derived from spectra is not directly related to the coordinates of molecules in the unit cell. The spectra are, however, sensitive to the values of internal coordinates which define molecular structure. Thus they provide a basis for testing the degrees of equivalence of structures. Very often also, specific spectral features can be identified with particular functional groups defined by distinctive sets of internal coordinates. 

The objectives of the CIPM-MRA are to establish the degree of equivalence of measurement standards maintained by NMIs to provide for the mutual recognition of calibration and measurement certificates issued by NMIs thereby to provide governments and other parties with a secure technical foundation for wider agreements related to international trade, commerce, and regulatory affairs. It is founded on the efforts of each individual NMI to base its measurements and measurement uncertainties on SI units. 

Degrees of Equivalence of Measurement Standards and Measurement Capabilities... 

Indicates the degree of equivalence for SMU resulting from the subsequent bilateral comparison between SMU and PTB. 

A large number of experimental data on friction factors of smooth pipe and pipes of varying degrees of equivalent roughness have been obtained and the data correlated. For design purposes to predict the friction factor/and, hence, the frictional pressure drop of round pipe, the friction factor chart in Fig. 2.10-3 can be used. It is a log-log plot of/... 

The same distinction must be made for hydrogen-bond affinity scales. When the heats of reaction of, for example, 4-fluorophenol with a series of bases are measured in a ternary system (4-FC6H40H/B/solvent), a solute scale is obtained, whereas measurements on the binary system 4-FC6H4OH/B, corrected by the heats of solution of a similar but non-HBD probe such as 4-FC6H40Me (the so-called pure base calorimetric method) [10], furnish a solvent scale. The degree of equivalence of solute and solvent scales will be considered later. 

---