Exercise

# Evaluate the 10-fold CV error

In this exercise, you'll evaluate the 10-fold CV Root Mean Squared Error (RMSE) achieved by the regression tree `dt`

that you instantiated in the previous exercise.

In addition to `dt`

, the training data including `X_train`

and `y_train`

are available in your workspace. We also imported `cross_val_score`

from `sklearn.model_selection`

.

Note that since `cross_val_score`

has only the option of evaluating the negative MSEs, its output should be multiplied by negative one to obtain the MSEs. The CV RMSE can then be obtained by computing the square root of the average MSE.

Instructions

**100 XP**

Compute

`dt`

's 10-fold cross-validated MSE by setting the`scoring`

argument to`'neg_mean_squared_error'`

.Compute RMSE from the obtained MSE scores.