Decision trees

- [Voiceover] The first procedure in machine learning that…we want to talk about is decision trees.…It reminds me of the bumper sticker that says…trees are the answer and in machine learning they often are.…This is an example of a very simple decision tree.…Let's take a quick look at the anatomy of this chart.…You haven't called a root node, that's the starting point,…it's at the top, then you start having these splits…which are indicated on branches…or edges is the mathematical term.…You have nodes which are decision points.…

And then you finish with the leaves or the terminal nodes…which are the last category that your data ends up in.…Now, decision trees come in two general categories.…There are classification trees, which use quantitative…and categorical data model categorical outcomes,…and there are regression trees, that use the same kind…of quantitative and categorical data,…except this time to model quantitative outcomes.…Sort of like multiple regression…but trees are often easier to set up and interpret.…