Major Tasks in Data Preprocessing Data cleaning Fill in missing values, smooth noisy data, identify or remove outliers and resolve inconsistencies Data integration Integration of multiple databases, data cubes, or files Data reduction Dimensionality reduction ◆ Numerosity reduction ◆ Data compression Data transformation and data discretization ◆ Normalization Concept hierarchy generation 同济大学软件学院 ool of Software Engineering. Tongpi Unversity4 Major Tasks in Data Preprocessing ◼ Data cleaning ◆ Fill in missing values, smooth noisy data, identify or remove outliers, and resolve inconsistencies ◼ Data integration ◆ Integration of multiple databases, data cubes, or files ◼ Data reduction ◆ Dimensionality reduction ◆ Numerosity reduction ◆ Data compression ◼ Data transformation and data discretization ◆ Normalization ◆ Concept hierarchy generation