ESDU 92022 uses the analysis of a set of measurements of screen and touchdown speeds, rates of descent at the screen and touchdown, and airborne time to illustrate multiple linear regression. In this context it is usual to derive two separate correlations: the relationship between the mean rate of descent and the rates of descent at the screen and touchdown, and the relationship between the ratio of the screen speed to the touchdown speed and the rates of descent at the screen and touchdown. In both cases the significance of the derived fit is verified using the F variance ratio test. The use of the results to derive certification values of airborne distance is discussed. An introduction to statistical techniques for use in the analysis of aircraft performance data is given in ESDU 91017.