Example of statistical techniques applied to analysis of landing ground roll distance measurements. (Linear regression@ correlation coefficient and F test.)
ESDU 92021 uses the analysis of a set of measurements of approach speed and associated landing ground roll distance to illustrate the use of linear@ two variable regression. Regression is used twice: firstly@ on an empirical basis@ a linear relationship is assumed between the two variables@ and@ secondly@ taking account of the physics of the manoeuvre@ a linear relationship is assumed between the square of the approach speed and the ground roll. In both cases@ the significance of the derived fit is verified using the F variance ratio test and the correlation coefficient. Both fits are found to be excellent@ although the latter is clearly the better physical model. An introduction to statistical techniques for use in the analysis of aircraft performance is given in ESDU 91017.