Linear regression is one of the most popular and widely used statistical techniques in data science. It is used to model the relationship between a dependent variable, or the response variable, and one or more explanatory variables. Ordinary Least Squares (OLS) is a technique that can be used to carry out linear regression. In this blog post, we will take a look at what OLS is and how it works. We will cover topics such as why it’s so useful, how to implement it with Python, and when to use other methods instead.

What is the Ordinary Least Square (OLS) Method?

The Ordinary Least Square (OLS) Method is a statistical technique used for estimating the unknown parameters in a linear regression model. The OLS method minimizes the sum of the squared residuals, which is the difference between the actual value and the predicted value of the dependent variable. The OLS method can be used to estimate the coefficients of the independent variables, as well as the intercept term.

How to Use the OLS Method?

The Ordinary Least Squares (OLS) method is a well-known technique for estimating the parameters of a linear regression model. In this blog post, we will describe how to use the OLS method to estimate the parameters of a linear regression model.

First, let’s briefly review the concept of linear regression. Linear regression is a statistical technique that is used to model the relationship between a dependent variable and one or more independent variables. The dependent variable is the variable that is being predicted, while the independent variables are the variables that are used to predict the dependent variable.

In order to use the OLS method to estimate the parameters of a linear regression model, we need to have a dataset that contains values for both the dependent variable and the independent variables. Once we have this dataset, we can then use mathematical techniques to estimate the values of the coefficients (β0 and β1) in the linear regression equation: 𝑦=𝑏₀+𝑏₁𝑥+𝔼

The coefficient estimates obtained using the OLS method are sometimes called “least squares estimates” because they minimize the sum of squared residuals. Residuals are the differences between the actual values of the dependent variable and the predicted values (i.e., 𝑦−ˆ𝑦). So, by minimizing the sum of squared residuals, we are trying to find parameter estimates that result

Advantages and Disadvantages of the OLS Method

There are both advantages and disadvantages to using the Ordinary Least Squares (OLS) method for linear regression. Some of the advantages include that the OLS method is relatively easy to use and understand, and that it can be applied to a wide variety of data sets. Additionally, OLS usually provides good results even when there are outliers in the data.

However, there are also some disadvantages to using OLS. One potential disadvantage is that OLS can be sensitive to extreme values in the data set, which can lead to inaccurate results. Additionally, OLS assumes that there is a linear relationship between the dependent and independent variables, which may not always be the case in real-world data sets.


The ordinary least squares method is a powerful and popular tool for linear regression. It can be used to uncover the relationships between different variables, predict future trends, and provide useful insight into complex datasets. Although other methods of regression may have their own advantages, OLS remains one of the most widely used due to its simplicity, accuracy and flexibility. With an understanding of this method and some basic knowledge in statistics, anyone can start using OLS to analyze data efficiently and accurately.

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James William
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