Supervised Learning
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Supervised learning entails learning a mapping between a set of input variables (typically a vector) and an output variable (also called the supervisory signal) and applying this mapping to predict the outputs for unseen data. Supervised methods attempt to discover the relationship between input variables and target variables. The relationship discovered is represented in a structure referred to as a model. Usually models describe and explain phenomena, which are hidden in the dataset and can be used for predicting the value of the target attribute knowing the values of the input attributes.
Supervised learning is the machine learning task of inferring a function from supervised
training data (set of training examples). The training data consists of a set of training
examples. In supervised learning, each example is a pair consisting of an input object and a
desired output value. A supervised learning algorithm analyzes the training data and
produces an inferred function.
From Statistics for Machine Learning (
Many supervised machine learning methods fall in to this category:
Classification problems
Logistic regression
Lasso and ridge regression
Decision trees (classification trees)
Bagging classifier
Random forest classifier
Boosting classifier (adaboost, gradient boost, and xgboost)
SVM classifier
Recommendation engine
Regression problems
Linear regression (lasso and ridge regression)
Decision trees (regression trees)
Bagging regressor
Random forest regressor
Boosting regressor - (adaboost, gradient boost, and xgboost)
SVM regressor
Some of the issues to consider in supervised learning are as follows:
Bias-variance trade-off
Function complexity and amount of training data
Dimensionality of the input space
Noise in the output values
Heterogeneity of the data
Redundancy in the data
Presence of interactions and non-linearity
Typically the problems will look like
These problems each contain a target of interest (Did the Titanic passenger survive? Did the customer churn? What’s the MPG?) and a set of training data with known values of the target. Indeed, most problems in machine learning are supervised in nature, and most ML techniques are designed to solve supervised problems.
Supervised Learning:
is like learning with a teacher
training dataset is like a teacher
the training dataset is used to train the machine
Example:
Classification:Machine is trained to classify something into some class.
classifying whether a patient has disease or not
classifying whether an email is spam or not
Regression:Machine is trained to predict some value like price, weight or height.
predicting house/property price
predicting stock market price