Proteomic Mass Spectrometry II: Cleaning and Preprocessing Keith Baggerly Department of Biostatistics & Applied Mathematics M.D. Anderson Cancer Center Abstract: In order to make sense of mass spectrometry proteomic data, it is often necessary to "clean" the data so that the final contrasts between disease and control spectra will make sense. In this talk, we first present a case study involving the study of MALDI mass spectra derived from serum for the investigation of lung cancer, using it to illustrate the need for baseline subtraction, normalization, and other processing steps. We then introduce some of the methods that we are currently using to process like spectra, ranging from the undecimated wavelet transform for smoothing and baseline subtraction to the use of simple averaging to improve peak detection.