Testing Your AISee For Yourself
To make K-Fold Cross-Validation crystal clear, go ahead and test it yourself! In the interactive simulation below, we are using a simple linear regression model.
Try grabbing the slider and dragging the value of to change the number of folds used in the Cross-Validation. Watch what happens as the original dataset gets sliced and rotated:
Because each "fold" is forced to study a slightly different combination of data points, every single fold produces a slightly different trendline. The magical final test grade is completely evaluated by taking the
A Hidden Tradeoff!
While playing around with the simulation, you may have observed something interesting: the lines of best fit wildly jump around far more for purely low values of than they do for higher values.
This strange behavior isn't an optical illusion. It is actually a direct result of our old archnemesis: The Bias-Variance Tradeoff. Let's break down exactly why this happens in the next section!