Feature relevance analysis and dimensionality reduction
The goal of feature relevance and selection is to find the features that are discriminating with respect to the target variable and help reduce the dimensions of the data [1,2,3]. This improves the model performance mainly by ameliorating the effects of the curse of dimensionality and by removing noise due to irrelevant features. By carefully evaluating models on the validation set with and without features removed, we can see the impact of feature relevance. Since the exhaustive search for k features involves 2k – 1 sets (consider all combinations of k features where each feature is either retained or removed, disregarding the degenerate case where none is present) the corresponding number of models that have to be evaluated can become prohibitive, so some form of heuristic search techniques are needed. The most common of these techniques are described next.
Feature search techniques
Some of the very common search techniques employed...
