Proficiency-testing participants

Proficiency testing for CRTU analysis (which should be performed with CDU and B2MU analyses to evaluate the results properly) also is recommended. In the U.S., only the College of American Pathologists (CAP) currently conducts CRTU proficiency testing participating laboratories should be accredited for CRTU analysis by the CAP. 

The Secretariat shall inform the proficiency test participants before the test of the purpose and the scenario of the test. After completion of the test by the participating laboratories, the... 

General Lab. and Pharma. Lab. participate In proficiency-testing studies and market surveillance studies organised by European Department for Quality of... 

Peer review This involves setting up mechanisms for mutual review of dmg regulation systems. It serves as a means of external auditing, whereby the performance of one agency can be compared with that of others. Systems for international peer comparison of QC laboratories are one example. Proficiency tests are performed by the participating laboratories in such a way that each laboratory learns how well it is performing in comparison with the others. 

Table 14 can be regarded as providing a reasonable overall picture, even if the results cannot applied to any particular case. However, if the underlying principle is accepted, it becomes clear that improvements in a single stage, for example the reduction of instrument variation, has a negligible beneficial effect (if this variation was not outside the normal range ). Even if the contribution of repeatability is re-duced to zero, the cumulative uncertainty is reduced by 10% only, i.e. from 2.2 to y(0.0)2 (0.8)2 (1.0)2 + (1.5)2 = 2.0. This statistical view of errors should help to avoid some unnecessary efforts to improve, e.g., calibration. Additionally, this broad view on all sources of error may help to detect the most important ones. Consequently, without participation in proficiency tests, any method validation will remain incomplete. 

A proficiency testing scheme tests the performance of the participating laboratories whereas a collaborative study is used to test the performance of a particular method. 

The assigned value is the value attributed to the quantity being measured in the proficiency testing exercise. It can be considered the target value for participants. There are a number of different approaches to determining the assigned value. These are by use of ... 

If the analytical method used by participants in the proficiency testing round has been validated by means of a formal collaborative trial, then the repeatability and reproducibility data from the trial can be used. The repeatability standard deviation gives an estimate of the expected variation in replicate results obtained in a single laboratory over a short period of time (with each result produced by the same analyst). The reproducibility standard deviation gives an estimate of the expected variation in replicate results obtained in different laboratories (see Chapter 4, Section 4.3.3 for further explanation of these terms). 

En numbers are used when the assigned value has been produced by a reference laboratory, which has provided an estimate of the expanded uncertainty. This scoring method also requires a valid estimate of the expanded uncertainty for each participant s result. A score of En < 1 is considered satisfactory. The acceptability criterion is different from that used for z-, z - or zeta-scores as En numbers are calculated using expanded uncertainties. However, the En number is equal to zeta/2 if a coverage factor of 2 is used to calculate the expanded uncertainties (see Chapter 6, Section 6.3.6). En numbers are not normally used by proficiency testing scheme providers but are often used in calibration studies. 

It is always useful to consider the performance in a proficiency testing round in a wider context. One of the main factors to consider is the performance of all of the participants in the round. If the majority of the results are satisfactory, but yours is not, this is likely to indicate a problem in your laboratory. However, it is worth remembering that your laboratory may have got the correct result and the other participants are in error In addition, if many other participants also have unsatisfactory results, there is still a problem, but it is less likely to be in your laboratory. 

Making the Most of Participation in Proficiency Testing Schemes... 

Participation in proficiency testing schemes can bring significant benefits to laboratories. However, the proficiency testing scheme itself cannot cause improvements in laboratory performance. It is up to the participants to use the feedback they receive from the scheme to monitor their performance and to implement improvements where necessary. 

Participation in proficiency testing schemes is an ongoing activity. It is therefore useful to monitor performance over a period of time and to look for trends. Performance over time can be demonstrated statistically by using measures such as RSZ and SSZ (see Section 7.3.4) but as mentioned previously, these can be misleading. It is better to monitor performance scores by plotting them on a... 

This chapter has considered two of the types of interlaboratory comparison exercise in which your laboratory may participate. It is important to remember that proficiency testing schemes and collaborative studies have different aims. The former is a test of the performance of the laboratory, whereas the latter is used to evaluate the performance of a particular analytical method. Laboratories should participate in proficiency testing schemes (where an appropriate scheme is available) as this provides an independent check of the laboratory s performance. This chapter has described the key features of proficiency testing schemes and explained how the results from participation in a scheme should be interpreted. 

Participation in Proficiency Testing (PT) schemes/interlaboratory comparisons and review of data... 

As shown above, these include a laboratory to be third-party assessed to international accreditation standards, to demonstrate that it is in statistical control by using appropriate internal quality control procedures, to participate in proficiency testing schemes which provide an objective means of assessing and documenting the reliability of the data it is producing and to use methods of analysis that are fit-for-purpose . These requirements are summarised below and then described in greater detail later in this chapter. 

The need for laboratories carrying out analytical determinations to demonstrate that they are doing so competently has become paramount. It may well be necessary for such laboratories not only to become accredited and to use fully validated methods but also to participate successfully in proficiency testing schemes. Thus, proficiency testing has assumed a far greater importance than previously. 

The list has been constructed on the premise that contractors will use methods of analysis that are appropriate and accredited by a third party (normally UKAS), participate in and achieve satisfactory results in proficiency testing schemes and use formal internal quality control procedures. In addition, Parts B and C are made available to the potential contractors so that they are aware of what other demands will be made of them and can build the costs of providing the information into their bids. 

Do you participate in proficiency testing schemes If so, which schemes ... 

In proficiency tests the mean of the participants results is often used as a conventional trae value. 

Verification is confirmation by examination and provision of objective evidence that specified requirements have been fulfilled. ISO 9000 2005 Proficiency testing is a periodic assessment of the performance of individual laboratories and groups of laboratories that is achieved by the distribution by an independent testing body of typical materials for unsupervised analysis by the participants. [lUPAC Orange Book]... 

In accreditation the assessment team should consist of assessors/technical experts able to assess all relevant issues including the competence of the staff of the laboratory. This competence needs to be documented by relevant academic/technical qualifications, experience and training as well as successful participation in proficiency testing. 

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