# How a decision tree selects a feature on which a tree needs to be split?

## How a decision tree selects a feature on which a tree needs to be split?

Steps to split a decision tree using Information Gain: For each split, individually calculate the entropy of each child node. Calculate the entropy of each split as the weighted average entropy of child nodes. Select the split with the lowest entropy or highest information gain.

### How does a decision tree decide the threshold value to handle numerical features?

16. How does a Decision Tree handle continuous(numerical) features? Decision Trees handle continuous features by converting these continuous features to a threshold-based boolean feature. To decide The threshold value, we use the concept of Information Gain, choosing that threshold that maximizes the information gain.

#### How does a decision tree decide to split?

At every node, a set of possible split points is identified for every predictor variable. The algorithm calculates the improvement in purity of the data that would be created by each split point of each variable. The split with the greatest improvement is chosen to partition the data and create child nodes.

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How does a decision tree work for numerical data?

A decision tree is built top-down from a root node and involves partitioning the data into subsets that contain instances with similar values (homogenous). We use standard deviation to calculate the homogeneity of a numerical sample. If the numerical sample is completely homogeneous its standard deviation is zero.

Can you apply decision trees to a numeric variable?

Decision trees can handle both categorical and numerical variables at the same time as features, there is not any problem in doing that.

## What split criteria?

The splitting criteria used by the regression tree and the classification tree are different. Like the regression tree, the goal of the classification tree is to divide the data into smaller, more homogeneous groups. Homogeneity means that most of the samples at each node are from one class.

### What is first split in decision tree?

To build the tree, the information gain of each possible first split would need to be calculated. The best first split is the one that provides the most information gain. This process is repeated for each impure node until the tree is complete.

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#### How do you determine the threshold value?

1. Adjust some threshold value that control the number of examples labelled true or false.
2. Generate many sets of annotated examples.
3. Run the classifier on the sets of examples.
4. Compute a (FPR, TPR) point for each of them.
5. Draw the final ROC curve.

How do I choose the right threshold?

To find the right threshold for your application, first you need to collect a representative set of images. The set of images should be representative, not just with regard to their number, but in the quality and types of the images that may be encountered in the stream.

How to split a decision tree using information gain?

Steps to split a decision tree using Information Gain: 1 For each split, individually calculate the entropy of each child node 2 Calculate the entropy of each split as the weighted average entropy of child nodes 3 Select the split with the lowest entropy or highest information gain 4 Until you achieve homogeneous nodes, repeat steps 1-3 More

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## How to create your own decision tree?

Create your own Decision Tree! At every node, a set of possible split points is identified for every predictor variable. The algorithm calculates the improvement in purity of the data that would be created by each split point of each variable. The split with the greatest improvement is chosen to partition the data and create child nodes.

### How to split a decision tree using reduction in variance?

Here are the steps to split a decision tree using reduction in variance: 1 For each split, individually calculate the variance of each child node 2 Calculate the variance of each split as the weighted average variance of child nodes 3 Select the split with the lowest variance 4 Perform steps 1-3 until completely homogeneous nodes are achieved

#### What is a decision tree algorithm?

If you are unsure about even one of these questions, you’ve come to the right place! Decision Tree is a powerful machine learning algorithm that also serves as the building block for other widely used and complicated machine learning algorithms like Random Forest, XGBoost, and LightGBM.