This proficiency test aims to check the density calculations/conversions of the participants.The scheme was organised before and in that final the following was concluded: 'In general the results are an eye-opener. In practice, the spread in the results will be the sum of the measurement and the conversion. And most probably the spread caused by the measurement will be much larger than the spread in the conversion, which should be close to zero. However, the spread in the conversions only, as observed in this study, is far from zero and sometimes even larger than the requirements of the Standard. Furthermore a large number of uncorrect results - results that deviated more than 0.0001 kg/l from the theoretical value - was reported. For some exercises, this number of uncorrect results is even over 65% of the total amount of results'.
Therefore, the PT was repeated.

This proficiency test Density deviates from regular I.I.S. schemes in two ways:

1. it is organised on special request of a third party. Therefore, in contrast to regular I.I.S. proficiency tests, this scheme is not open to all interested laboratories, but only for those invited to participate; for those laboratories participation is even mandatory.
2. the PT is a paper Round Robin for Density calculations/conversions. So, no samples are distributed, but a number of pages containing the data on density calculations.

On 20 Oct. 98 the proficiency test started with 114 participants out of 52 different countries. The participants were sent four pages containing the data for this paper PT scheme (no sample was sent). Most laboratories received the pages and additional instructions via electronic mail (e-mail); some laboratories could not be reached in this way and to them the mail was sent by post. They were requested to let a technician calculate the densities, to report the calculated densities, applied corrections and tables on the forms and to return the completed forms via airmail (and/or fax) to the Institute.
As always in I.I.S. proficiency tests, each laboratory was asked to report only the determinations for which it has experience.

The deadline for reporting results is set on 20 Nov. 98. A laboratory that sends in results after deadline will definitely will not get direct feedback in case any of its results are suspect! So be in good time to get the most out of this proficiency test.