The training set is the part that estimates model parameters.
The validation set is the part that assesses or validates the predictive ability of the model.
The test set is a final, independent assessment of the model’s predictive ability. The test set is available only when using a validation column (see Descriptions of Launch Window).
Randomly divides the original data into the training and validation data sets. The Validation Portion (see Descriptions of Launch Window) on the platform launch window is used to specify the proportion of the original data to use as the validation data set (holdback).