However, a recent study of eight normalization procedures  states that it is better to use a local than a global (such as the TIC) normalization method. In other words, the rescaling parameter of the spectra should be estimated by windowing the axis rather than a global computation over all intensities. In addition, median values have proven to be more robust than averages as scale factors against possible outlying peaks , and their use is also very well-established in other normalization processes, like, for example, DNA microarrays .
Accepting both observations, we propose combining both approaches in our normalization technique: use local estimators over windows with rescaling to the median value of the TIC. The window width is a free parameter tuned by an expert. As a default value, for MALDI/SELDI spectra we suggest using 200 units.