a-c – The effect of low wavelength cut-off as a function of increasing errors in magnitude. An example of the effect of the low-wavelength cut-off as a function of increasing errors in spectral magnitude on the performance as judged by the parameters A) ζ, B) r, and C) δ, respectively, using the SIMPLS algorithm with the SP175 dataset. The different curves on each plot represent different results obtained after applying progressively larger scale factors to represent errors in magnitude. The numbers represent the variance of the normal distribution from which the scaling factors were randomly chosen. These were for the α-helix (H) secondary structure component as assigned by DSSP.