[jira] [Updated] (MADLIB-1205) Add gini importance to DT

["Rahul Iyer (JIRA)" <ji...@apache.org>]

     [ https://issues.apache.org/jira/browse/MADLIB-1205?page=com.atlassian.jira.plugin.system.issuetabpanels:all-tabpanel ]

Rahul Iyer updated MADLIB-1205:
-------------------------------
    Summary: Add gini importance to DT  (was: Add gini importance to DT and RF)

> Add gini importance to DT
> -------------------------
>
>                 Key: MADLIB-1205
>                 URL: https://issues.apache.org/jira/browse/MADLIB-1205
>             Project: Apache MADlib
>          Issue Type: New Feature
>          Components: Module: Decision Tree, Module: Random Forest
>            Reporter: Rahul Iyer
>            Assignee: Rahul Iyer
>            Priority: Major
>             Fix For: v1.15
>
>
> From the Breiman resource that we use for random forest:
> {quote}Gini importance
> {quote}
> {quote}Every time a split of a node is made on variable m the gini impurity criterion for the two descendent nodes is less than the parent node. Adding up the gini decreases for each individual variable over all trees in the forest gives a fast variable importance that is often very consistent with the permutation importance measure.
> {quote}
> We can add a similar measure in our DT and RF code and distinguish this from our permuted importance metric by calling the current metric as {{oob_variable_importance}} and this new metric as {{impurity_variable_importance}}.



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