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{{see also|Machine learning terms}}
==Introduction==
In the field of [[machine learning]], noise refers to the presence of unwanted or irrelevant data that can have a detrimental effect on the performance and accuracy of a model. Noise can be introduced during the data collection process, data preprocessing, or through inherent randomness in the data itself. This article will provide an overview of the various types of noise, their sources, and their impacts on machine learning models.

==Sources of Noise==
Noise in machine learning can originate from various sources and can be categorized into the following types:

===Measurement Noise===
Measurement noise, also known as [[observation noise]], is the type of noise that arises due to errors in the process of collecting and recording data. This can be caused by imprecise measurement instruments, human errors, or limitations in the data collection process. Measurement noise often leads to discrepancies between the true values and the observed values in the dataset.

===Inherent Noise===
Inherent noise is the type of noise that is present within the data itself and is not a result of the data collection process. This type of noise is usually due to the inherent randomness or complexity of the underlying phenomena being modeled, and it is often challenging to remove or minimize.

===Process Noise===
Process noise is the noise that is introduced during the data preprocessing stage. This includes errors in data cleaning, feature extraction, and feature engineering. Process noise can be minimized by using appropriate data preprocessing techniques and by carefully selecting the features to be used in the model.

==Impact of Noise on Machine Learning Models==
The presence of noise in machine learning models can have various negative impacts on their performance and accuracy. Some of these impacts include:

===Overfitting===
Overfitting occurs when a model learns the noise in the data instead of the underlying patterns, leading to poor generalization to unseen data. This can be addressed by using techniques such as [[regularization]], [[cross-validation]], and model complexity control.

===Reduced Model Accuracy===
Noise can lead to reduced accuracy in machine learning models, as it can cause the model to make incorrect predictions or classifications. This can be mitigated by using more robust algorithms that are less sensitive to noise or by employing noise reduction techniques during data preprocessing.

===Increased Computational Complexity===
The presence of noise can increase the computational complexity of machine learning models, as the model may require more complex algorithms or a larger number of features to effectively model the underlying patterns. This can be addressed by using dimensionality reduction techniques, such as [[principal component analysis]] or feature selection methods.

==Noise Reduction Techniques==
Several noise reduction techniques can be employed to minimize the impact of noise on machine learning models. Some of these techniques include:

===Data Cleaning===
Data cleaning involves the process of identifying and correcting errors, inconsistencies, and inaccuracies in the dataset. This can include removing duplicate records, filling in missing values, and correcting errors in the data.

===Feature Selection===
Feature selection is the process of selecting a subset of relevant features for use in the model, with the aim of reducing noise and improving model performance. Methods such as [[recursive feature elimination]], [[mutual information]], and correlation-based feature selection can be used to identify and select the most relevant features.

===Dimensionality Reduction===
Dimensionality reduction techniques, such as principal component analysis or [[t-distributed stochastic neighbor embedding]] (t-SNE), can be employed to reduce the number of features in the dataset while maintaining the majority of the information. This can help in reducing noise and improving the performance of machine learning models.

==Explain Like I'm 5 (ELI5)==
Noise in machine learning is like a messy room where you are trying to find your favorite toy. The mess (unwanted or irrelevant data) makes it harder for you to find your toy (the pattern or information you want to learn). There are different types


[[Category:Terms]] [[Category:Machine learning terms]] [[Category:Not Edited]] [[Category:updated]]