A series of statistical analyses was performed to determine the degree of 'correlation' that exists between two specific short tests (STs) and the Federal Emission Certification Test Procedure (FTP) for new vehicles. This work was performed to determine if 'reasonable correlation with certification test procedures' exists; this is a condition precedent to the promulgation of regulations that impose the in-use warranty provisions of Sec. 207(b) of the Clean Air Act of 1970 upon the motor vehicle manufacturers. The basis for the analyses was ST and FTP test data from (a) three 100-vehicle 1975 model year fleets located in (1) Chicago, Illinois, (2) Houston, Texas, and (3) Phoenix, Arizona, (b) a 117-vehicle 1975 model year fleet located in Denver, Colorado, (c) a 147-vehicle 1974 model year fleet located in the greater Detroit, Michigan area, and (d) a 40-vehicle catalyst-equipped '1975-prototype' experimental fleet that had been operated in California in Ford vehicle test programs. Each of the vehicles in these fleets was tested by the FTP, the Federal Short Cycle, and the Federal 3-Mode. Two different statistical analysis methods were used to assess 'correlation'--a conventional correlation analysis, and a contingency table analysis.