For Linear Regression, R-squared is a statistical term which indicates how close the data are to the fitted regression line.
R-Squared is also known as coefficient of determination.
R-squared = Explained variation in data / Total variation in data
R-squared = 1 – (RSS/TSS)
RSS = Sum of squares of difference between predicted value and actual value
TSS = Sum of squares of difference between mean value and actual value
How to calculate R-Squared using Sklearn for Linear Regression.
from sklearn.metrics import r2_score
rsquared = r2_score(y_true,y_pred)
Below picture depicts how all the data point may not fall on the fitted regression line.
Note that the value of R-squared does not indicate the performance of the Linear Regression model, hence you should analyze residuals by calculating Root Mean Squared Error or RMSE as well.
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