R Squared Theory  Practical Machine Learning Tutorial with Python p.10  Summary and Q&A
TL;DR
This tutorial explains squared error and coefficient of determination (Rsquared) in linear regression, and how to calculate them in Python.
Key Insights
 Linear regression accuracy is determined using squared error, which measures the distance between data points and the best fit line.
 ❎ Squared error is squared to ensure positive values and penalize outliers.
 Coefficient of determination, or Rsquared, allows us to compare the accuracy of the best fit line to the mean of the dependent variable.
 💯 A higher Rsquared value indicates a better fit, with 1 being a perfect fit.
 📈 Rsquared is an important metric for evaluating the performance of a linear regression model.
 ❎ Squared error and Rsquared can be calculated in Python using the provided formulas.
 😝 Rsquared values closer to 1 indicate a stronger correlation between the independent and dependent variables.
Transcript
hello everybody and welcome to Part 10 of our machine learning tutorial Series in this part what we're going to be talking about is we've been talking about linear regression and we've got to the point where we could calculate the best fit line in our python code but now the question is how good of a fit is our best fit line how do we determine the... Read More
Questions & Answers
Q: What is the purpose of calculating the coefficient of determination in linear regression?
The coefficient of determination, or Rsquared, measures the proportion of variance in the dependent variable that can be explained by the independent variable(s). It indicates how well the best fit line fits the data and ranges from 0 to 1.
Q: Why is squared error used instead of absolute error in linear regression?
Squaring the error values ensures that we only deal with positive values and penalizes outliers. Absolute error would not have the same effect and might lead to less accurate results.
Q: Can the value of Rsquared be negative?
No, the value of Rsquared can never be negative. It ranges from 0 to 1, where 0 indicates the regression model does not explain any variance in the data and 1 indicates a perfect fit.
Q: How do you interpret an Rsquared value of 0.8?
An Rsquared value of 0.8 suggests that 80% of the variance in the dependent variable can be explained by the independent variable(s). It indicates a relatively good fit between the data and the best fit line.
Summary & Key Takeaways

This tutorial is part of a series on machine learning and focuses on calculating the accuracy of a best fit line in linear regression.

It introduces the concept of squared error and explains why it is used to determine accuracy, emphasizing the importance of penalizing for outliers.

The tutorial also explains the calculation of the coefficient of determination (Rsquared) and provides examples of good and bad values.