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QL Pay

Quality Level and Pay Factor Analysis (QL Pay) is used to track Materials accepted on a statistical basis. The program provides for:

  • Calculation of quality levels based on estimated percent defective
  • Calculation of pay factors based on preassigned risk levels
  • Portrayal of control charts and histograms
  • Hypothesis testing of multiple laboratory test results
  • Determination of random sampling locations based on total quantity of materials or roadway stationing in English or metric units, and more.

All Federal Lands Highway divisions currently support the Standard Specifications for Construction of Roads and Bridges on Federal Highway Projects issued in 1996 (FP-96), in 2003 (FP-03), and in 2014 (FP-14); including their supplemental specifications.

Subsection 106.05 - Statistical Evaluation of Work and Determination of Pay Factor (Value of Work of the FP-96), outlines statistical acceptance procedures for materials and gives details pertaining to the computation of pay factors. QL Pay was developed for the purpose of tracking materials and computing pay factors in accordance with the FP specifications. The original program was written in 1983 and ran on a VAX 1140 main frame computer. Today, QL PAY is used on individual PCs by Project Engineers, Contractors, QA/QC Personnel, Material Engineers, and Others.

QL Pay is a statistical method used to determine the estimated percentage of a material that falls outside the established specification limits. It is expressed in terms of percent defective (percent outside the specification limits). When work is accepted based on statistical evaluation using quality level analysis, both the Government and Contractor assume some risk. The Government's risk is the probability that work of a rejectable quality level will be accepted. The Contractor's risk is the probability that work produced at an Acceptable Quality Level (AQL) will be rejected or accepted at a reduced contract price.

AQL is the highest percentage of work outside the specification limits that is considered acceptable for payment at contract price. There are 2 categories available for evaluation. The first category is based on an AQL of five percent defective. The second category is based on an AQL of ten percent defective. In both cases, the Contractor's risk (beta) is five percent regardless of sample size. The Government's risk (alpha) varies depending on the number of samples evaluated. Based on the number of samples analyzed and the estimated percent defective a pay factor is calculated which is adjusted to maintain the Contractor's risk constant.

As an incentive to produce uniform quality work and to offset the Contractor's risk, a final payment greater than the contract price may be obtained under certain conditions.


QL-PAY 6 requires the .Net Framework Version 4. The .Net Framework may be found at QL-PAY 6 was developed on Windows 7 and may not run on other versions of Windows.

If you wish to request an electronic copy on CD-ROM or for installation support, please email Installation Support is limited to installation issues only. 

For technical questions, email