Samples that drive quality

"I don’t think we would have the quality of the AB program that we do [without] having their involvement, maintaining the standard that we do. I think it’s helped us immensely."

New Hampshire Department of Transportation

Alan Rawson, Bureau of Materials & Research Administrator

55+ years of experience
PSP participants
samples shipped per year
laboratory assessments per year
accredited labs

Frequently Asked Questions - Proficiency Samples

Additional information on the Proficiency Sample Program can be found in the In Focus newsletter.
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How do I get started?
What are the requirements for participating laboratories?
To participate, a laboratory must be equipped to perform some or all of the standard AASHTO or ASTM tests on soils, aggregates, asphalt binder, asphalt emulsion, or hot mix asphalt.
What tests am I required to perform on a sample?
A non-accredited laboratory may perform any (or all) of the AASHTO or ASTM tests on a sample pair. Accredited laboratories must perform all offered test methods within the scope of their accreditation (i.e. every accredited test).
How have labs performed in the past?
AASHTO re:source provides Reports and a Compilation of Statistics from previous samples.
How can I submit my results?
You may submit your results online (you must be logged in to do this) or you may fax or mail us your results.
How do I save an electronic copy of my ratings sheet?
Sign in and access your ratings sheet on the website. To save the ratings page as a file on your computer click on "File" and "Save As" and designate the location to which you want the file saved.
Can I get more time to submit my data?
Generally, AASHTO re:source does not offer extensions on the deadline for data submission (closing date) for proficiency samples. Entering data on the website or via e-mail or fax after the deadline does not guarantee that your laboratory’s data will be included in the round analysis. Revisions to closing dates have been made due to changes in sample production or events that have impacted a significant portion of participants (i.e., natural disasters).
How and when do I respond to low ratings on a proficiency sample?
Within 60 days of the date on the final report, an accredited laboratory receiving a +/- 2, +/- 1, or zero rating must investigate the root cause of the low ratings. A standard Proficiency Sample Corrective Action Report Form is available. Keep a copy for your own records, but these records are not required to be submitted to AASHTO re:source.

AASHTO Accredited laboratories are required to submit a corrective action report for low sample ratings that result in a suspension. The corrective action report must be submitted with the results of an extra proficiency sample (blind) or with the next sequential round when seeking reinstatement for that suspension. This corrective action report will be reviewed for effectiveness by a Quality Analyst.

Read more about responding to low ratings in the newsletter article, I Received A Low PSP Score, What Next?

What do the ratings for “repeatability (within-lab)” mean?
Repeatability is an estimate of the variation in results that you might expect if you repeated the same test over and over in your laboratory. The within-lab rating is based on the difference between the two individual lab results, but also subtracts out any actual differences between the two sample materials (the manner is similar to what we have always done when computing single operator statistics for the compilation of statistics).

An “individual within-lab value" is determined for each lab as follows:
  1. Individual Within-Lab Value = [(Yi-Xi)-(Yavg-Xavg)]/(square root of 2)
  2. The standard deviation of those values is the repeatability (or within-lab) standard deviation, 1S.
  3. The "Within-Lab Ratings" are determined using the "Individual Within-Lab Values" and the "Within-Lab Standard Deviation, 1S" to determine within-lab Z-Scores. Then, the same rating scheme is used as for the individual samples.
Do laboratories need to respond to low ratings for “repeatability (within-lab)” on a proficiency sample?
No. You should examine why your within-lab results may not be as consistent in your laboratory as in other laboratories, but AASHTO Accredited laboratories are not required to investigate the root cause of the low ratings.
How can I change data I have already submitted?
If it is before the samples’ posted closing date, you can change/update the data previously submitted. Navigate to the “View Sample Round Result Confirmation” page as you would to initially submit your data. (This is the page you saw after you first submitted your results.) Click on the “Overwrite Data” button at the bottom of the page to make the desired changes.

If it is after the samples’ posted closing date and analysis has already begun, your data cannot be changed.
I don’t see the answer to my question. Can I ask a new question?
Yes, you can. Send us your question, and we might add it to the FAQ page. You may also want to check the FAQ pages for the other programs as well as review previous newsletter articles.