New customer? Register here

The gold standard for laboratory accreditation in the construction industry

Search for an Accredited Lab

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

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


Proficiency Sample Reports

In order to view your individual reports for Proficiency Samples, you must first be logged in with a valid laboratory account.  Upon logging in, select 'View Your PSP Ratings'.

You can also view the general results of a Sample Round Analysis and a Compilation of Statistics.

Data Reports

Statistical Summary Tables

The statistical summary tables show data for each test property analyzed both before and after the removal of results beyond three standard deviations. Each table provides the following information:

Column 1 - Abbreviated titles and units for each test property analyzed
Column 2 - The number of laboratories included in each analysis
Columns 3 & 6 - The average values for both samples of the pair
Columns 4, 5, 7 & 8 - The between-laboratory standard deviation and coefficients of variation

Youden Diagrams

Youden diagrams are a graphical representation of the data received for each test property (after the removal of outliers). The points on the diagrams are located by plotting the test value reported for the odd numbered sample of a pair from a given laboratory on the horizontal axis, against the test value reported for the even numbered sample by the same laboratory on the vertical axis.

The vertical and horizontal dashed lines represent the average values for all the results on the first sample and the second sample, respectively. These lines divide the diagram into four quadrants, numbered from 1 through 4, beginning in the upper right quadrant and proceeding counterclockwise. The number of plotted points may not agree with the total number of data pairs included in the analysis because a few points may be off the diagram, and some points may represent several data pairs which are identical.