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regression in machine learning

Module - 3 Supervised Learning

Lesson - 2 Regression

**Overview**

Regression is a prescient modelling procedure utilized in machine learning. It is utilized to foresee a continuous value, such as a cost or a probability, from a given set of independent variables. It is a supervised learning algorithm, meaning that it requires labelled training data to create exact models. Regression algorithms can be linear or nonlinear and can be utilized for both classification and regression errands. Regression can be used to distinguish patterns in information, reveal connections between factors, and make expectations almost long haul.

**What is regression?**

Regression in Machine Learning is a procedure utilized to foresee the output of a given input. It could be a supervised learning algorithm, meaning it is prepared utilizing labelled data.

An illustration of regression within the industry is anticipating the cost of a house. In this situation, we would utilize regression to prepare a machine learning model utilizing labelled data of house costs and their related characteristics such as square footage, number of rooms, number of lavatories, area, etc. Once the machine learning model is trained, we can then input new characteristics of a house and the model will predict the associated price of the house. This can be used by real estate agents to help set prices for their clients.

Regression has also been used by companies to predict the demand for their products. By training a machine learning model with labelled data of sales and associated characteristics such as advertising spend, seasonality, etc., companies can predict how much demand there will be for their products. This can help them better manage their inventory and set prices accordingly.

Regression in machine learning is a process of predicting a continuous or real value output, such as stock prices, house prices or GDP growth, based on independent variables or features. A supervised learning problem involves finding a function that best maps the relationship between the input features and the output variable.

**Definition and purpose of regression**

Regression is a statistical analysis technique used to determine the relationships between a dependent variable and one or more independent variables. It is used to analyze the effects of multiple variables on a single outcome variable. It is commonly used in forecasting, forecasting financial markets, and determining the cause of a particular phenomenon. Regression can help identify trends, relationships, and patterns that can provide insight into the data and its underlying structure.

**Types of regression**

- Multiple Linear Regression: This sort of regression employs different independent variables to foresee the esteem of one dependent variable.
- Polynomial Regression: This sort of regression is utilized to model nonlinear relationships between the independent and dependent factors.
- Logistic Regression: This type of regression is used to predict a binary (yes/no) outcome based on one or more independent variables.
- Ridge Regression: This type of regression is utilized to diminish the complexity of a show and avoid overfitting.
- Lasso Regression: This sort of regression is utilized to decrease the complexity of a demonstrate and progress its exactness.

**Dataset structure of regression model**

The structure of a regression model dataset typically includes the following columns:

- A target column, which contains the outcome or dependent variable that the model is attempting to predict.
- An ID column, which contains a unique identifier for each observation in the dataset.
- A set of feature columns, which contain the independent variables that the model uses to make predictions.
- A timestamp column, which contains the time at which each observation was recorded.

**Applications of regression**

**Financial matters:**Regression is utilized to analyze financial information and recognize designs and relationships between diverse factors. For case, financial analysts might utilize relapse examination to investigate the relationship between GDP and work or the affect of charges on customer investing.**Psychology:**Regression is utilized to analyze information from mental tests and superior get it how certain factors connected with one another. For illustration, analysts might utilize relapse to investigate the connections between IQ, instructive achievement, and work execution.**Public Health:**Relapse is utilized to get it the connections between distinctive wellbeing results and chance variables. For illustration, disease transmission experts might utilize relapse to analyze the relationship between corpulence and heart infection or smoking and lung cancer.

**Advantages of Regression:**

**Helps in Predictive Analysis:**Regression analysis is useful for predictive analysis as it helps in predicting the value of the dependent variable based on the values of the independent variables.**Helps in Identifying the Relationship:**Regression analysis helps in identifying the nature and strength of the relationship between the dependent and independent variables.**Useful in Decision Making:**Regression analysis is useful in decision making as it provides a quantitative assessment of the relationship between variables.**Helps in Finding the Best Fit:**Regression analysis helps in finding the best fit between the independent and dependent variables, which can help in understanding the underlying mechanisms of the relationship.

**Disadvantages of Regression:**

**Sensitive to Outliers:**Regression analysis is sensitive to outliers, which can affect the results of the analysis.**Linearity Assumption:**Regression analysis assumes a linear relationship between the dependent and independent variables. If this assumption is violated, the results of the analysis may not be accurate.**Overfitting:**Regression analysis can suffer from overfitting, which occurs when the model is too complex and fits the training data too closely, resulting in poor performance on new data.**Limited to Continuous Variables:**Regression analysis is limited to continuous variables, and it may not be suitable for analyzing categorical or binary data.

**Algorithms in Regression**

**Linear Regression:**Linear regression is one of the most commonly used algorithms for regression problems. It is used to estimate the relationship between a dependent variable and one or more independent variables by fitting a linear equation to observed data.**Logistic Regression:**Logistic regression is a method used to fit a regression model when the dependent variable is binary or ordinal. It is used to predict the probability of an event occurring, such as the probability of a person being diagnosed with a disease or the probability of a person buying a product.**Polynomial Regression:**Polynomial regression is a type of regression analysis in which a polynomial function is used to fit a given set of data points. It is used to model non-linear relationships between the independent and dependent variables.**Decision Tree**: A decision tree is a supervised learning algorithm that can be used for both regression and classification problems. It is a decision tree-based model that builds a regression model in the form of a tree structure. It splits the data into subsets based on the most significant independent variables.**Support Vector Machine:**A support Vector is a type of Support Vector Machine (SVM) that is used for regression problems. It is based on the principle of finding a hyperplane that best separates a set of data points. The separating hyperplane is chosen in such a way that the distance between the data points and the hyperplane is as large as possible.**Random Forest:**Random forest is an ensemble learning method that combines multiple decision tree models to create a more powerful model. It is a supervised learning algorithm that uses multiple decision trees to create an aggregate model that is more accurate than any of the individual decision trees.

**Conclusion**

After utilizing regression within the industry, companies are presently able to foresee the cost of a house based on its characteristics, as well as anticipate the request for their items based on related characteristics such as promoting spend and regularity. This has permitted them to superior oversee their stock and set costs in like manner.

**Key takeaways**

- Regression is a supervised learning technique used to predict a continuous numerical outcome.
- It is based on the relationship between the independent and dependent variables.
- Linear regression is the most common type of regression and is used to model linear relationships between a dependent variable and one or more independent variables.
- Regularization techniques such as L1, L2, and Elastic Net can be used to improve the performance of linear regression models.
- Nonlinear regression models such as polynomial regression and support vector regression can be used to model nonlinear relationships between the independent and dependent variables.
- Evaluating the performance of a regression model is important to ensure that it is able to accurately predict the desired outcome.
- Cross-validation is a common method used to evaluate the performance of regression models.
- Feature selection and engineering can be used to improve the performance of regression models by reducing the number of input features and transforming the data.

**Quiz**

**What is the most popular method of evaluating the accuracy of a regression model?**- Root Mean Square Error
- Mean Absolute Error \R
- squared
- Adjusted R-squared

**Answer**: c. R-squared

**What is the goal of linear regression?**- To minimize the data points
- To minimize the error
- To maximize the error
- To maximize the correlation between the independent and dependent variables

**Answer**: b. To minimize the error

**What type of supervised learning problem is linear regression?**- Classification
- Clustering
- Regression
- Dimensionality Reduction

**Answer**: c. Regression

**What is the most common form of regularization used in linear regression?**- L1 regularization
- L2 regularization
- Dropout
- Early stopping

**Answer**: b. L2 regularization

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