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  • Writer's pictureLawrence Cummins

Standard regression algorithms used in data science.


Standard regression algorithms are widely used in data science to predict the relationship between a dependent variable and one or more independent variables. There are various types of regression algorithms, each with its own strengths and weaknesses.

 

Linear Regression:

Linear regression is perhaps the most well-known and widely used regression algorithm. Using a linear equation, it models the relationship between a dependent variable, y, and one or more independent variables, x. The mathematical formula for simple linear regression is:

 

y = β0 + β1x + ε

 

Where y is the dependent variable, x is the independent variable, β0 is the intercept, β1 is the slope, and ε is the error term.

 

Ridge Regression:

Ridge regression is a shrinkage method used to address the problem of multicollinearity in linear regression. It adds a penalty term to the ordinary least squares objective function to prevent overfitting. The mathematical formula for ridge regression is:

 

minimize ||y - Xβ||^2 + λ||β||^2

 

Where y is the dependent variable, X is the matrix of independent variables, β is the vector of coefficients, and λ is the regularization parameter.

 

Lasso Regression:

Lasso regression is another shrinkage method that is used to select a subset of relevant features and perform regularization at the same time. It adds an L1 penalty term to the ordinary least squares objective function. The mathematical formula for lasso regression is:

 

minimize ||y - Xβ||^2 + λ||β||

 

Where y is the dependent variable, X is the matrix of independent variables, β is the vector of coefficients, and λ is the regularization parameter.

 

Polynomial Regression:

Polynomial regression is a linear regression in which the relationship between the independent and dependent variables is modeled as an nth degree polynomial. The mathematical formula for polynomial regression is:

 

y = β0 + β1x + β2x^2 + ... + βnx^n + ε

 

Where y is the dependent variable, x is the independent variable, β0, β1, β2, ..., βn are the coefficients, and ε is the error term.

 

Support Vector Regression (SVR):

Support vector regression is a non-parametric regression algorithm that uses support vector machines to perform regression. It aims to find a hyperplane in a high-dimensional space with the maximum margin to the data points. The mathematical formula for support vector regression is:

 

minimize 1/2||β||^2 + C∑ξi + ε

 

Subject to yi - βxi - ε ≤ ξi

              βxi - yi - ε ≤ ξi

              ξi ≥ 0

             

Where yi is the dependent variable, xi is the independent variable, β is the coefficient vector, C is the penalty parameter, ξi is the slack variable, and ε is the epsilon tube.

 

Decision Tree Regression:

Decision tree regression is a non-parametric regression algorithm that uses a tree-like structure to model the relationship between the independent and dependent variables. The mathematical formula for decision tree regression is:

 

y = ∑yi(x)

 

Where y is the dependent variable, x is the independent variable, and yi(x) is the prediction of the ith leaf in the decision tree.

 

Random Forest Regression:

Random forest regression is an ensemble learning method that combines multiple decision trees to improve the accuracy and robustness of the regression model. The mathematical formula for random forest regression combines the decision tree regression formulas for each tree in the forest.

 

y = (1/N)∑∑yi(x)

 

Where y is the dependent variable, x is the independent variable, N is the number of trees in the forest, and yi(x) is the prediction of the ith tree.

 

Gradient Boosting Regression:

Gradient boosting regression is another ensemble learning method that combines multiple weak learners to create a strong regression model. It uses gradient descent to minimize the residual errors at each iteration. The mathematical formula for gradient boosting regression is:

 

F0(x) + Σmfm(x)

 

Where F0(x) is the initial prediction, fm(x) is the prediction of the mth weak learner, and m is the number of iterations.

 

There are various standard regression algorithms, each with its own mathematical formula and unique characteristics. Understanding these algorithms and their mathematical formulas is crucial for effectively applying them in data science projects. With a strong grasp of these algorithms, data scientists can accurately predict the relationship between variables and make informed decisions based on the results.

 

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