What is overfitting in machine learning?
Tags: machinelearning
Published: 2023-11-22 05:53:33

Overfitting is a crucial concept in machine learning, and it occurs when a model trained on a dataset learns the training data to an excessive degree, capturing noise and random fluctuations in the data rather than the underlying patterns. In simpler terms, it's when a machine learning model becomes too complex and fits the training data so closely that it loses its ability to generalize to new, unseen data, leading to poor performance on real-world tasks.

To understand overfitting better, let's delve into a more detailed explanation of this phenomenon.

Machine learning models aim to learn the underlying relationships and patterns in data so they can make accurate predictions or classifications on new, unseen data. To do this, they are trained on a labeled dataset, which consists of input features (variables) and corresponding target outputs (labels). During training, the model adjusts its internal parameters to minimize the difference between its predictions and the actual target values in the training data. This process is guided by a loss function, which quantifies the error between the predicted and actual values.

The goal of training a machine learning model is to strike a balance between two opposing forces: bias and variance. Bias refers to the error introduced by approximating a real-world problem, which may be complex, by a simplified model. High bias can cause the model to underfit the data, meaning it fails to capture the underlying patterns, leading to poor performance on both the training and test datasets. On the other hand, variance refers to the model's sensitivity to small fluctuations or noise in the training data. High variance can lead to overfitting, where the model becomes too flexible and captures noise rather than true patterns.

Overfitting typically occurs when a model becomes excessively complex, with too many parameters or degrees of freedom. Such a model can fit the training data extremely well, achieving a low training error. However, this overzealous fitting of the training data can lead to a significant increase in the model's variance. As a result, when the model encounters new, unseen data (the test data), it struggles to generalize and makes inaccurate predictions because it has essentially memorized the training data instead of learning the underlying patterns. Apart from this by obtaining a [Machine Learning Course](https://www.edureka.co/masters-program/machine-learning-engineer-training), you can advance your career in  Machine Learning. With this course, you can demonstrate your expertise in designing and implementing a model building, creating AI and machine learning solutions, performing feature engineering, many more fundamental concepts.

**Several factors contribute to overfitting:**

**Model Complexity:** Complex models, such as deep neural networks with many layers or decision trees with numerous nodes, are more prone to overfitting because they have a high capacity to represent intricate relationships in the training data.

**Small Dataset:** With a small dataset, there's less information available to the model, making it easier for it to memorize the data rather than generalize from it.

**Noisy Data:** If the training data contains noise or errors, the model may mistakenly fit these noisy patterns, leading to overfitting.

**Irrelevant Features:** Including irrelevant or redundant features in the dataset can confuse the model and lead to overfitting. Feature selection or engineering techniques can help mitigate this issue.