# Cross-validation (/tutorials/cross-validation)

[Members-only tutorial](https://members.vectorbt.pro/tutorials/cross-validation/)

When trading strategies that have shown strong performance in backtesting are applied to new data,
they often prove to be fragile or may even fail catastrophically. This usually happens due to
backtest overfitting, which can be detected and avoided with proper cross-validation.

✅ We will start with manual cross-validation, then cover different splitting schemes and
techniques for analyzing split distributions. Finally, we will go over how to automate various
cross-validation steps, from splitting regular arrays and complex VBT objects to testing entire
parameter-based and ML-based pipelines 🔥

*   [Workflow](https://members.vectorbt.pro/tutorials/cross-validation/workflow): Understand validation schemes and diagnose backtest overfitting
*   [Splitter](https://members.vectorbt.pro/tutorials/cross-validation/splitter): Learn how to build a splitter for cross-validation in VectorBT PRO
*   [Applications](https://members.vectorbt.pro/tutorials/cross-validation/applications): Learn how to apply a splitter for cross-validation in VectorBT PRO