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4 types of machine learning
Supervised (inductive) learning
Unsupervised learning
Semi-supervised learning
Reinforcement learning
Which type of machine learning?
Training data includes desired outputs (Y)
Function approximation
Supervised (inductive) learning
Which type of machine learning? Training data does not include desired outputs (Y)
Describe given dataset
-given examples of X, how can we describe it summarize this dataset?
Unsupervised learning
Which type of machine learning?
Training data includes a few desired outputs
Semi-supervised learning
Which type of machine learning?
Rewards from sequence of actions
Model optimal decision of agents based on actions, stated and rewards
Reinforcement learning
Examples of supervised (inductive) learning
Linear regression, logistic regression, decision trees and random forest, XG Boost, Support Vector Machine
Examples of unsupervised learning
Clusters
Dimensionality reduction
Goal of decision trees
Classify or predict an outcome based on a set of predictors; the output is a set of rules
Example:
Goal: classify a record as will accept or will not accept
Rule might be:
-if income is greater than 10 then class = 0
Example of discrete supervised learning
Classification or categorization
Example of discrete unsupervised learning
Clustering
Example of continuous supervised learning
Regression
Example of continuous unsupervised learning
Dimensionality reduction
What is the Gini index
A measure of the total variance across all the K classes (in the mth region)
- small value when pmk is close to 0 or 1
- aka node purity
- small value indicates that a mode mostly contains observations from a single class
A small déviance of a classification tree is a sign that
The tree provided good fit to the training data
