From Theory to Reality

This interactive workbench demonstrates why rigorous backtesting is non-negotiable in quantitative finance. Explore how common pitfalls, validation methods, and risk management choices transform a strategy from a "false discovery" into a potentially robust system.

The Seven Deadly Sins of Backtesting

Flawed backtests create the illusion of profitability. Understanding these common biases is the first step toward building a strategy that works in the real world, not just on paper.

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Overfitting

Curve-fitting a model to historical noise instead of finding a true signal. The strategy perfectly memorizes the past but has no predictive power.

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Look-Ahead Bias

Using information in the simulation that would not have been available at the time, like using a day's closing price to trade at that day's open.

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Survivorship Bias

Testing only on assets that "survived" to the present, ignoring failed or delisted companies where the strategy would have lost money.

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Ignoring Costs

Forgetting to model transaction costs like commissions and slippage, which can turn a profitable strategy into a losing one.

The Interactive Validation Lab

Financial data is not random. Standard cross-validation causes "data leakage," leading to inflated results. Select a method below to see how respecting the timeline produces a more realistic performance estimate.

Walk-Forward Analysis (WFA) is the industry standard. It simulates reality by training the model on a past window of data and testing it on a subsequent, unseen window. This process is rolled forward in time, creating a chain of true out-of-sample results and providing a robust defense against overfitting.

The Bet Sizing Simulator

A good signal is useless without proper risk management. Bet sizing determines how much capital you risk per trade. Select a method to see its profound impact on portfolio growth, volatility, and risk of ruin.

Fixed Fractional sizing risks a constant percentage of equity per trade (e.g., 2%). It is excellent for capital preservation and compounding, automatically reducing risk during drawdowns.

Performance Dashboard

A holistic view of performance requires a suite of metrics. This dashboard reflects the results of the choices made in the Bet Sizing Simulator, revealing the trade-offs between return, risk, and volatility.

Sharpe Ratio

1.21

Max Drawdown

-18.5%

Calmar Ratio

0.98

Profit Factor

1.82