Quote from annaland:
"In the financial industry, there are three main approaches to investment: the
fundamental approach, where strategies are based on fundamental economic
principles, the technical analysis approach, where strategies are based on past
prices behavior, and the mathematical approach where strategies are based on
mathematical models and studies. The main advantage of technical analysis is
that it avoids model specification, and thus calibration problems, misspecifi-
cation risks, etc. On the other hand, technical analysis techniques have limited
theoretical justifications, and therefore no one can assert that they are riskless,
or even efficient."