The metaphor of Data Mining means that there are treasures (or nuggets) hidden under mountains of data, which may be discovered by specific tools Data Mining is concerned with data which were collected for another purpose: it is a secondary analysis of data bases that are collected Not Primarily For Analysis, but for the management of individual cases(Kardaun, T Alanko, 1998) Data Mining is not concerned with efficient methods for collecting data such as surveys and experimental designs(Hand, 2000) Beijing, 2008 5Beijing, 2008 5 ◼ The metaphor of Data Mining means that there are treasures (or nuggets) hidden under mountains of data, which may be discovered by specific tools. ◼ Data Mining is concerned with data which were collected for another purpose: it is a secondary analysis of data bases that are collected Not Primarily For Analysis, but for the management of individual cases (Kardaun, T.Alanko,1998) . ◼ Data Mining is not concerned with efficient methods for collecting data such as surveys and experimental designs (Hand, 2000)