Exemplary estimation of the nonlinearity by interpolation of the data onto itself. Here we linearly interpolate between the first and third datapoints and determine the difference between the measured datapoint between and the interpolated one. The sum of these residuals divided by the number of residuals in the full dataset is taken into account as an additional uncertainty of the ratio. For details of the analysis procedure see the main text. Error bars correspond to the 1 statistical uncertainty that is propagated by Gaussian uncertainty propagation.
