Difference between the calibration function of a 10 kPa full scale CDG obtained in one case by modelling the calibration data (f_t), and in the other case by applying a correction factor k_CDG to the previous calibration function (k_CDG × f_t−1). Here k_CDG is the slope coefficient of the least squares fit to a straight line that is used to estimate the reference pressure p_FPG as a function of the CDG pressure modelled with the function (f_t−1), in the range between 40% and 80% of the full scale of the CDG. This difference is plotted together with the residuals of the model: (f_t − p_FPG).