In the building of a decision tree, when it's better to prefer the information gain criterion to the gain ratio criterion ? And why ?
If two attributes with different number of possible values (categories), have the same Enthropy, Info Gain cannot differentiate them (Decision tree algorithm will select one of them randomly). In the same situation Gain Ratio, will favor attribute with less categories.
Gain ratio strategy, leads to better generalization (less overfitting) of DT models and it is better to use Gain ration in general.
Even if one would like to favor attributes with more categories, Info Gain wouldn't be a good choice since it does not differentiate between attributes with different numbers of categories.
Hope this helps!