The grid ranks the importance of each variable in the current model.
Some variables can be completely unimportant and be safely removed. This can be tested by adding randomly generated numbers as inputs and checking the importance of these variables once the model is built.
Note: for large data sets calculating the importance can be time consuming. Each time the importance screen is revisited, the importance is not recalculated. If the model has been further trained then it is necessary to press the 'Recalculate' button.
