# Validate your model

The simplest way is to create your model using a random base selection. You can create a holdout sample by simply dragging off this selection and changing the logic to NOT, to select everybody not in the training data used to build the model.

## Create a validation cube

In the sections *[Using a random Base Selection](<https://help.apteco.com/en/faststats/modelling/decision-tree/setting-up/base-selection/#using-a-random-base-selection>)* and *[Using a Random Base Selection to Validate your Model](<https://help.apteco.com/en/faststats/modelling/decision-tree/setting-up/random-base-selection-validation/index.md>)* it explains how you can create a cube to show the Analysis % in the training and holdout samples.