Backtesting Validity
Backtesting validity is the degree to which a trading strategy's historical performance accurately predicts its potential for future success. It involves running a strategy against past market data to evaluate its profitability and risk profile.
In the cryptocurrency domain, validity is often compromised by "look-ahead bias," where the model uses information that would not have been available at the time of the trade, or by ignoring realistic transaction costs and slippage. If the backtest does not accurately reflect the market microstructure of the time, the strategy will likely fail when deployed live.
Ensuring validity requires meticulous data handling, including the use of out-of-sample testing and realistic simulations of market impact. It is the ultimate test of a model's reliability before real capital is committed.