6 Chapter 1 IntroduCtIon to data MInIng
data warehouse has to be prepared according to the expectations of the
data-mining algorithm used. Sometimes information in addition to the
raw data may need to be provided for the execution of the algorithm.
Sometimes multiple tables are required by the algorithm. It is the ultimate
task of the pre-processor to prepare the input data for use by the data-
mining algorithm.
1.2.2 Data Warehousing
Data warehousing is the process of storing as much data as possible (relevant
to the task) and retrieving any part or all of it for analysis. It involves the
merging of data, the cleaning up of data errors, and the storing of histori-
cal information about the data. It is often expensive, and ...