# Regularization in Machine Learning

We are very familiar with the word Machine Learning nowadays. Machine Learning technologies are used in everywhere. Many IT companies use this type of technologies to improve their product. In Machine Learning the main thing is prediction of output. The Machine Learning model is trained by a set of data. Then it is test by the test data set. It is often seen that the model works well in training data set but it can’t perform well with the test data set. To solve this problem we can use one technique which is regularization. In this article we will discuss about the regularization technique in details. Let’s understand the concept of regularization.

## What is Regularization?

One of the most crucial ideas in Machine Learning is regularisation. It is a method for preventing the model from overfitting by providing it with more data. The Machine Learning model may occasionally perform well with training data but poorly with test data. When dealing with unseen data by introducing noise in the output, it means the model is unable to anticipate the result and is therefore referred to as being overfitted. The use of a regularisation approach can solve this issue. By lowering the magnitude of the variables, this strategy can be applied to keep all variables or features in the model. Consequently, it keeps the model's generality and accuracy.

## What are Overfitting and Undefitting?

We provide some data for our Machine Learning model to learn from. Data fitting is the act of plotting a set of data points and constructing the best fit line to reveal the relationship between the variables. The optimal fit for our model is when it can identify all relevant patterns in our data while avoiding noise, or random data points and pointless patterns. If we give our Machine Learning model too much time to examine the data, it will discover numerous patterns in it, including ones that are superfluous. On the test dataset, it will learn extremely quickly and adapt very effectively. It will pick up on significant trends and noise in our data, but it won't be able to forecast on other datasets because of this. Overfitting is a situation where the Machine Learning model attempts to learn from the specifics as well as the noise in the data and tries to fit each data point on the curve.

## Regression Techniques

There are two main types of regularization techniques: Ridge Regularization and Lasso Regularization.

**Ridge Regularization: **It is also referred to as Ridge Regression and modifies over- or under-fitted models by applying a penalty equal to the sum of the squares of the coefficient magnitude. As a result, coefficients are produced and the mathematical function that represents our Machine Learning model is minimised. The coefficients' magnitudes are squared and summed. Ridge Regression applies regularisation by reducing the number of coefficients.

**Lasso Regularization: **By imposing a penalty equal to the total of the absolute values of the coefficients, it alters the models that are either overfitted or underfitted. Lasso regression likewise attempts coefficient minimization, but it uses the actual coefficient values rather than squaring the magnitudes of the coefficients. As a result of the occurrence of negative coefficients, the coefficient sum can also be 0.

## What does Regularization achieve?

The variance of a basic least squares model means that it won't generalise well to data sets other than its training set. Regularization dramatically lowers the model's variance while maintaining or even increasing its bias. The impact on bias and variance is thus controlled by the tuning parameter, which is employed in the regularisation procedures discussed above. As the value of increases, the coefficients' values decrease, lowering the variance. Up to a degree, this rise in is advantageous because it just reduces variance (avoiding overfitting), without losing any significant data features. However, after a certain value, the model begins to lose crucial characteristics, leading to model bias and underfitting. Consequently, the value of λ should be carefully selected.

## Conclusion

You don't need anything more complicated than this to begin the regularisation process. It is a practical method that can aid in enhancing the precision of your regression models. Scikit-Learn is a well-liked library for putting these algorithms into practise. It features a fantastic API that allows you to set up and execute your model with just a few lines of Python code.