Machine Learning - Machine Learning, Knowledge Discovery in Databases (KDD) and Data Mining

Machine Learning, Knowledge Discovery in Databases (KDD) and Data Mining

Two terms are commonly confused, as they often employ the same methods and overlap significantly. They can be roughly defined as follows:

• Machine learning focuses on prediction, based on known properties learned from the training data.
• Data mining (which is the analysis step of Knowledge Discovery in Databases) focuses on the discovery of (previously) unknown properties on the data.

The two areas overlap in many ways: data mining uses many machine learning methods, but often with a slightly different goal in mind. On the other hand, machine learning also employs data mining methods as "unsupervised learning" or as a preprocessing step to improve learner accuracy. Much of the confusion between these two research communities (which do often have separate conferences and separate journals, ECML PKDD being a major exception) comes from the basic assumptions they work with: in machine learning, performance is usually evaluated with respect to the ability to reproduce known knowledge, while in KDD the key task is the discovery of previously unknown knowledge. Evaluated with respect to known knowledge, an uninformed (unsupervised) method will easily be outperformed by supervised methods, while in a typical KDD task, supervised methods cannot be used due to the unavailability of training data.