Contractor versus agency verification (F and t tests)

23 CFR 637 · FHWA-RD-02-095 Appendix F

Explained inVerification of Contractor Test Results

Calculator

Contractor versus agency verification (F and t tests)

23 CFR 637 · FHWA-RD-02-095 Appendix F

Do the agency’s verification tests and the contractor’s quality control tests look like the same material? The F test compares their spread, then the t test compares their averages.

Contractor quality control results
Test	Result
1
2
3
4
5
6
7
8
9
10
11
12

Agency verification results
Test	Result
1
2
3
4
5
6
7
8

Specification

Level of significance, α

Appendix F recommends 0.01, which seldom calls matching results different; 0.05 and 0.10 are also used and find real differences more often.

Example values: in-place density as % Gmm, over the same period and by the same method. Your agency sets α.

All tools