Does linear regression need feature scaling?

Summary. We need to perform Feature Scaling when we are dealing with Gradient Descent Based algorithms (Linear and Logistic Regression, Neural Network) and Distance-based algorithms (KNN, K-means, SVM) as these are very sensitive to the range of the data points.

Why didn’t we apply feature scaling in simple linear regression model?

For example, to find the best parameter values of a linear regression model, there is a closed-form solution, called the Normal Equation. If your implementation makes use of that equation, there is no stepwise optimization process, so feature scaling is not necessary.

Is it necessary to do feature scaling?

When to do scaling? Feature scaling is essential for machine learning algorithms that calculate distances between data. If not scale, the feature with a higher value range starts dominating when calculating distances, as explained intuitively in the “why?” section.

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Do I need to normalize data before linear regression?

In regression analysis, you need to standardize the independent variables when your model contains polynomial terms to model curvature or interaction terms. This problem can obscure the statistical significance of model terms, produce imprecise coefficients, and make it more difficult to choose the correct model.

Should you scale target variable?

Yes, you do need to scale the target variable. I will quote this reference: A target variable with a large spread of values, in turn, may result in large error gradient values causing weight values to change dramatically, making the learning process unstable.

Is scaling required for random forest?

No, scaling is not necessary for random forests. The nature of RF is such that convergence and numerical precision issues, which can sometimes trip up the algorithms used in logistic and linear regression, as well as neural networks, aren’t so important.

Do we need to scale data for regression?

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You have come across a common belief. However, in general, you do not need to center or standardize your data for multiple regression. Different explanatory variables are almost always on different scales (i.e., measured in different units).

When should I scale my data?

You want to scale data when you’re using methods based on measures of how far apart data points, like support vector machines, or SVM or k-nearest neighbors, or KNN. With these algorithms, a change of “1” in any numeric feature is given the same importance.

Do we need to scale dependent variable?

Commonly, we scale all the features to the same range (e.g. 0 – 1). In addition, remember that all the values you use to scale your training data must be used to scale the test data. As for the dependent variable y you do not need to scale it.