10折交叉驗證（10-fold Cross Validation）
使用這種方法，我們將數據集隨機分成10份，使用其中9份進行訓練而將另外1份用作測試。該過程可以重複10次，每次使用的測試數據不同。
Leave-One-Out Cross-Validation
數據集中有n個樣本點時，n折交叉驗被稱爲留一法。
優點是穩定，同一個分類器和數據集用Leave-One-Out計算多次結果是一樣的。
缺點是計算開銷大。
Definition [1]
Leave-one-out cross-validation is a special case of cross-validation where the number of folds equals the number of instances in the data set. Thus, the learning algorithm is applied once for each instance, using all other instances as a training set and using the selected instance as a single-item test set. This process is closely related to the statistical method of jack-knife estimation (Efron, 1982).
Reference
[1] https://link.springer.com/referenceworkentry/10.1007%2F978-0-387-30164-8_469. Leave-One-Out Cross-Validation
