17th meeting on the Standard on Instrumental Odour Monitoring Systems took place last week

le . . Affichages : 4769

Bland Alman Plot2
   Last Monday took place the 17th meeting of Working Group 41 (WG41) that is dealing on the new standard for Instrumental Odour Monitoring Systems (IOMS). This meeting was focusing on the statistics behind the Quality Assurance Level 1 (QAL1) of IOMSs. There are some aspects that make IOMS special as compared to other Automatic Measuring Systems (AMS) and one of these aspects is the cost of comparing the electronic signal of the IOMS with that of the reference method EN 13725.

   One of the key issues addressed many times during the WG41 meetings is that of the number of samples that should be taken in order to make QAL1 checks viable for IOMS manufacturers. Dynamic Olfactometry comes at a cost and odour is not a substance, it is a class. The question is: how many samples should be taken in order to have a representative picture of the IOMS performance?

   Every year in Europe a few hundreds of AMS makers undergo QAL1 procedures like these of Germany. The idea is to evaluate the performance of the devices with a procedure that can be taken as a reference for further checks on QAL2, QAL3 and AST. However, life is easy when you have a stable reference material or an electronic reference method that can be used at a low cost per sample. Unfortunately, there is no reference material for ambient odours. Also, a sample that has to be analysed within 30 hours cannot be considered that stable.

   The more samples you take, the better confidence interval you get for your IOMS, but the cost of in this case grows quickly at range of 100-250 € per sample.

 This is when economics come at stake in the standardization world. It is also when statistics come to help economics.

  Two statistic approaches have being discussed during the last two meetings. The Bland–Altman plot approach and the Chebyshev's inequality.

   The Bland–Altman statistic approach is great to tackle the limitations that a correlation coefficient have, by looking at the differences of the results at different odour concentrations. However, this statistical approach assumes a normal distribution of the results. If there is a reduced number of samples, which is the scenario that the WG41 is targeting, then the power of the test to check if the data is really normal is very low, and therefore it is difficult to be certain that the data is gaussian-distributed.

 Chebyshev's inequality does not require a normal distribution of the data, so there is no need to have a large amount of data to check IOMS performance, and that is why the group decided to choose Chebyshev's inequality. Unfortunately that decision comes at a painful cost as it brings a wider confidence interval.

   A few other important issues were discussed during this meeting, but there is no space in this humble website to describe everything discussed in CEN working groups in detail, nor is the aim of this short text. Should you be interested in joining in the group and learning more about the future developments of this standard, we encourage you to contact your national standardization body to learn the procedure to be part of the group. Everyone is welcomed!

Picture source: wikipedia


   If you find this article interesting, you might also be interested in these articles:


Commentaires (0)

There are no comments posted here yet

Ajouter vos commentaires

  1. Posting comment as a guest.
Pièces jointes (0 / 3)
Share Your Location
  • Merry Christmas and happy festivities

    22 décembre 2021
     We hope you spend a wonderful time with your family and friends on these special dates. Many things have happened along this year 2021. It was a complicated year in general and particularly hard...
  • Drone-based environmental odour monitoring: SNIFFDRONE

    23 novembre 2021
       Wastewater treatment plants (WWTPs) produce gaseous emissions that might be olfactory annoying to the surrounding population. Current odour assessment methodologies are based on costly ...
  • Rubix changes to Ellona

    10 novembre 2021
        The French company Rubix, directed by the Mr. Jean-Christophe Mifsud, former CEO of Alpha MOS is switching to a more intelligence-focused service and that is why the company recentl...
  • Incidence with olores.org e-mails

    10 novembre 2021
       For technical reasons, we were unable to receive or send e-mails from our Olores.org accounts during a couple of weeks of November. So, if you contacted any of us from the 3rd November un...
  • New Development International handbook on Odour Management Plans

    29 juillet 2021
       The AMIGO Association is starting to take the first steps to create an International Guideline on Odour Management Plans (OMPS) and is looking for volunteers with experience in this fie...
  • Standard development on IOMS halted

    29 juin 2021
       Over five years have passed by since the first meeting of the Working Group (WG) 41 dealing with Instrumental Odour Monitoring Systems (IOMS). WG41 is under the umbrella of the Technical ...
  • Registration for the EN 13725 Interlaboratory Comparison 2021 is now open

    09 mars 2021
       Olfasense has announced the registration for the annual proficiency test for Dynamic Olfactometry according to the European Standard EN 13725. All laboratories around the world are invite...
  • IEEE looks for Standardization Volunteers

    26 janvier 2021
       The Institute of Electrical and Electronics Engineers (IEEE) has launched a new open call for experts to participate in several new standards related to Olfaction Devices. The organizatio...
  • What happened in 2020 in the odour management world

    31 décembre 2020
    The team of Olores.org would like to wish all its readers a Happy New Year. Again Olores.org has grown beyond our wildest expectations. In terms of readership, this year we got about 63,088 page views...
  • 1st Workshop of ASPIDI project in Puglia, Italy

    25 novembre 2020
       This Thursday, November 26th, at 15:00 (CET), the first workshop of the ASPIDI project (Automatic System Supported by the Population for the Identification of Diseases by Smelling Immunit...

REMARQUE ! Ce site utilise des cookies et autres technologies similaires.

Si vous ne changez pas les paramètres de votre navigateur, vous êtes d'accord. En savoir plus

J'ai compris