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FAQ

How can I treat multiple model output (such as time series)?

The objective function of a sensitivity analysis exercise is assumed to be a

scalar function. When the model has several output variables, the analysis has to be repeated several times, one for each output variable.

How can the Atomic Detectives' work answer to a forensic case?

Recognised as a centre of excellence by national and international policing

bodies, JRC-ITU has developed various methods that allow identification of the origin of intercepted material and the probable intended application. This needs to be done in a prompt manner, with first results available to be delivered to the appropriate authorities within 24 hours of a sample first arriving.

How do I compare my result with the certified values?

The underlying principle is that one has to check whether the difference bet

ween the measured result and the certified value is larger than the expanded combined uncertainty of measurement and certified value. This is done as follows:

1. Calculate the standard uncertainty of the certified value (uCRM). This is obtained by dividing the expanded uncertainty given on the certificate by the expansion factor (also stated on the certificate).
2. Estimate the measurement uncertainty (um) of the result. As a very rough approximation, the reproducibility standard deviation can be used
3. Combine the two uncertainties:
4. Check whether 2*uc is larger than the difference between the certified and the measurement value. If this is the case, the measurement result agrees within the limits of the respective uncertainties with the certified values

For example: Certified reference material BCR-605 (road dust) with a trimethyllead-content of 7.9 ± 1.2 µg/kg has been used. The analytical result was 11.10 µg/kg and the standard measurement uncertainty as determined in the method validation (um) is 15 %, i.e. 1.67 µg/kg. The difference between analytical result and certified value is therefore 3.2 µg/kg. Prior to the determination of the combined uncertainty, the standard uncertainty of the certified value of the reference material must be determined. The uncertainty of the certified value (UCRM) is given as 95 % confidence interval with 6 degrees of freedom as stated on the certificate. The factor of the t-distribution (t95, 6) is 2.447. The confidence interval must be divided by this factor to obtain the standard uncertainty of the certified value. This standard uncertainty (uCRM) is therefore:

The combined uncertainty (uc) of measurement and certified value is the square root of the quadratic sum of the individual uncertainties:

The results show that the uncertainty of the certified value has almost no influence on the combined uncertainty. This combined uncertainty is now multiplied with a coverage factor of 2 to obtain the expanded uncertainty (here 3.48 µg/kg). This expanded uncertainty is bigger than the difference between analytical results and certified values (3.2 µg/kg). Within the limits of the uncertainties, no method bias is visible.

How do I know whether the certified value is valid for my method?

There are two CRM properties that describe the usefulness of a material for

a certain method, namely traceability and commutability. Traceability describes what the certified value actually refers to including the definition of the measurand: is it about total or extractable element content, Kjeldahl or Dumans N? Commutability describes whether a material behaves similarly as a certain routine sample for a given method.

Therefore, one should check whether the certified value of a CRM is traceable to the same reference as one’s method. If this is not the case, the material is unsuitable.

Example: Certified values for dietary fibre traceable to a certain ISO method are only valid, if exactly this method is used.

Additionally, one should check whether commutability is ensured. If this is not the case, the material may be unsuitable.

How does the JRC encourage mobility of scientists?

Individual researchers can apply for positions within JRC Institutes in area

s linked to JRC's workprogramme, and funds are also available to support short-term visits. Applications from women scientists are particularly welcome.

How is the JRC funded?

The JRC is allocated an annual

ex.cfm?id=1460&lang=EN" title="JRC finances">budget of around €330 million for direct support to EU institutions from the Seventh Framework Programme (FP7). It earns up to a further 15% from competitive activities (participation in collaborative projects, technology transfer and work for third parties - including industry and regional authorities).

How is the JRC's work organised?

The JRC's

013.pdf" title="JRC Multi-Annual Workprogramme">Multi-Annual Work-programme (MAWP) 2007-2013, provides a general description of the line of work and the accompanying actions which are undertaken during the 7th Framework Programme (FP7) period. The Multi-annual work-programme is complemented, at the beginning of each year, by an annual work-programme, which details the Actions to be undertaken by the JRC for that year.

How long can I store my material?

CRMs should be used completely as soon as possible after receipt, because th

e producers cannot guarantee the stability of materials when stored outside their premises. If stored under the same condition as at IRMM, the materials can in principle be stored until the end of their shelf life, but beware: if some stability problems are discovered, IRMM will contact customers only down to a certain date.

How many forensic cases have been analysed at JRC-ITU?

In the last 20 years JRC-ITU has been analysing almost 50 cases of confiscat