Jan 13, 2012

BackTesting, the good guy or the bad guy?


On trading system developing, Backtesting is the process of testing a strategy on a financial historical data. However a backtest don´t represent necessarily the real performance of the system. It could easily made a overfitting, changing the parameters of the system, optimizing the system, but not realy outperforming because the parameters are overtrained to precisely this situation, with a high performance imprecision. The process of the system design needs a separate historical data for the data validation process.

The process of Optimization, the quality of the data, the indicators accuracy, for example, are details that must be looked inside. A system response, observed on the backtest graphic can present a very high sensitivity, changing drastically the performance with few parameters changes, indicating an imperfect optimization.

The quality of data and of the mathematical models as well as the process of optimization could talk more of a trading system than just a backtesting.

Rodrigo Sucupira Rodrigo Sucupira
Rodrigo is a Automation and Control Engineer - Escola Politécnica / USP. Interested on Financial Engineering, writes articles about Finance and Technology.
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