Preprocessing

Abstract

Textbook examples typically use clean, perfect data, allowing the techniques of interest to be explained and illustrated. However, in real life data are messy, noisy, incomplete, downright faulty, or a combination of these. The first step in any data analysis often consists of preprocessing to assess and possibly improve data quality. This step may actually take more time than the analysis itself, and more often than not the process consists of an iterative procedure where data preprocessing steps are alternated with data analysis steps.