Fig. 1

In a circadian time series proteomics experiment, protein intensities were measured every four hours for two days (PXD019431). To investigate the smoothness of the signal, replicates at each time point were shuffled randomly and reduced to a replicate number given in the legend. In each data reduction iteration curvature and slopes were determined. A: Protein intensity means at 12 time points were interpolated with cubic splines using natural boundary conditions [27]. The second derivative of the spline at the inner knots was determined as smoothness measure. B: Protein intensity means at 12 time points were interpolated with linear splines. The first derivative of the lines within the knot intervals was determined as smoothness measure. C: Variances of curvatures A and slopes B of the signal interpolation are calculated and plotted against the number of used replicates