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Proficiency Testing Plans: What You Need to Know

If you are seeking accreditation or are already an accredited laboratory, then you probably know you need to participate in proficiency testing (PT) and that you MUST have a PT plan. But that’s easier said than done.

So how do you go about developing a PT plan? What considerations should be made?

Start by looking at your organizational structure and ask yourself some questions. Are you a lab within a larger manufacturing company, or a commercial, third-party lab? What is your level of competency? Who are your stakeholders and what are their requirements? Next, review your scope of accreditation and at the same time consider the lab’s workload, any changes in standards, equipment, methods, or staffing, any past failures of PTs, any findings from internal audits, and any customer complaints. Essentially, your PT plan should take risk into account, so you want to identify those areas where there is greatest risk of failure. Remember, change introduces risk, so pay close attention to changes within the lab.

Next, you will want to structure your plan so that it covers at least one full accreditation cycle and covers each parameter within your scope over the allotted time. You will want to focus additional PTs where workload is heaviest, and on problem areas that may need improvements. You may want to use PTs to validate methods or the effectiveness of training. This should also be reflected in your PT plan. It is important to document the reasoning behind the structure of your PT plan because an AB may ask to see evidence that you took risk into account when developing your plan. You should also consult with your AB regarding their specific requirements related to proficiency testing.

Finally, a PT plan should be reviewed and modified periodically. Changes within the lab (staffing, equipment, standards, etc.) or unsatisfactory audit or PT results may require additional PTs to be introduced to your plan. Similarly, changes to your scope of accreditation will also influence your PT plan.

There are many benefits to regularly participating in proficiency testing beyond meeting the requirements for accreditation. PTs can demonstrate competency and/or identify potential problems. They can be used to validate new procedures or standards and are part of a robust quality control program. Remember, internal checks may not always reveal drift over time. Use of periodic, independent, external checks add an extra layer of confidence to your measurement results.

Fortunately, NAPT has a tool to help develop and maintain a lab’s PT plan. It’s free and can be found in your Customer Portal. If you don’t have an account with NAPT, you can sign up on our website: and click on Customer Portal, or go to

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