Anomaly Detection: What It Is and How to Use It in Machine Learning

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David Horvath


Anomaly detection is the identification of items, events, or observations that do not conform to an expected pattern or other items in a dataset. It has become an important area of machine learning in recent years because unstructured data (data that does not have a pre-determined structure) is becoming more and more common. In this blog post, we will discuss what anomaly detection is, how it can be used in machine learning, and some of the challenges associated with using machine learning for anomaly detection. We will also provide some examples of unstructured datasets and explain why validation of data is so important in this context.

What is an anomaly?

Before talking about anomaly detection, we need to understand what an anomaly is. An anomaly is a data point or event that does not conform to the expected pattern of the dataset. It could be an outlier, a noise, or something else entirely. Anomalies can be extremely difficult to identify because they often don’t follow patterns that are recognizable by traditional machine learning techniques.

Why do you need machine learning for anomaly detection?

This is a process that is usually conducted with the help of statistics and machine learning tools. Traditional anomaly detection techniques often involve manual analysis of data which is time-consuming and prone to human error. On the other hand, machine learning algorithms are able to analyze large datasets in a much faster and more accurate way. This makes it possible for organizations to quickly identify anomalies in unstructured data that could have otherwise gone undetected.

The majority of companies today that require outlier detection work with huge amounts of data: transactions, text, images, video content, etc. You would have to spend days going through all the transitions that happen inside a bank every hour, and more and more are generated every second. It is simply impossible to drive any meaningful insights from this amount of data manually.

Moreover, another difficulty is that the data is often unstructured, which means that the information wasn’t arranged in any specific way for the data analysis. For example, business documents, emails, or images are examples of unstructured data.

To be able to collect, clean, structure, analyze, and store data, you need to use tools that aren’t scared of big volumes of data. Machine learning techniques, in fact, show the best results when large data sets are involved. Machine learning algorithms are able to process most types of data. Moreover, you can choose the algorithm based on your problem and even combine different techniques for the best results.

Machine learning used for real-world applications helps to streamline the process of anomaly detection and save resources. It can happen not only post-factum but also in real time. Real-time anomaly detection is applied to improve security and robustness, for instance, in fraud discovery and cybersecurity.

What are anomaly detection methods?

Anomaly detection methods are used to identify unstructured data points that are out of the ordinary. Examples include unsupervised learning algorithms such as clustering, density-based methods, and anomaly detection using predictive models (like neural networks). Supervised learning techniques can also be used for anomaly detection if the labeled training dataset is available.

Clustering algorithms are unsupervised techniques used to identify anomalies. These methods divide the data into clusters based on similarities between the points. The model then predicts which cluster the unstructured data points should belong to and flags those that don’t fit in any of them as anomalous.

Density-based anomaly detection methods measure the distance between unstructured data points and then assign a probability score to each instance. Data points with a low probability of belonging to any cluster are seen as anomalies.

Predictive models can also be used for anomaly detection by comparing unstructured data points with what has already been learned from labeled training datasets. Models like neural networks are capable of analyzing unstructured data and flagging instances that don’t match what has been learned as anomalies.

In order to successfully apply machine learning for anomaly detection, it is essential to have well-validated datasets in which the anomalies are correctly labeled. This will ensure that unstructured data points can be accurately identified as either normal or anomalous. Additionally, unsupervised methods should be properly adjusted to the specific problem and data sets for optimal results.

Ultimately, machine learning for anomaly detection is a powerful way to quickly identify outliers in unstructured data. It allows organizations to detect anomalies faster and more accurately than ever before – improving security and streamlining fraud detection. It is essential, however, to have well-validated unstructured data sets for the best results.

Examples of unstructured datasets

An unstructured dataset is any data that does not have a pre-determined structure. This could include text, images, audio files, and videos. Here are some examples of unstructured datasets:

•  Natural language processing (NLP): Texts such as emails, documents, or social media posts.
•  Images: Photos, videos, medical images, or satellite images.
•  Audio files: Music recordings, voice recordings, or sound recordings.
•  Video files: Movies, television shows, or online tutorials.

Why validation of unstructured data is important?

It is essential to validate unstructured datasets before using them for anomaly detection. Validation ensures that unstructured data points are correctly labeled as either normal or anomalous. This allows machine learning algorithms to accurately identify anomalies and reduce the false positive rate. Additionally, unsupervised methods need to be properly adjusted to the specific dataset in order for them to work optimally. Therefore, validation is a key step in the application of machine learning for anomaly detection.

In conclusion, unstructured data is essential in today’s data-driven world and it is important to validate unstructured datasets before using them for machine learning. Anomaly detection methods are powerful tools to quickly identify outliers in unstructured data, but they need to be properly adjusted to the specific problem and data set for optimal results. With unstructured datasets correctly validated, machine learning algorithms will be able to accurately detect anomalies, resulting in improved security and streamlined fraud detection.

First of all, we at Lexunit tried to learn about the different types of anomaly detections and their use cases, then we implemented our own toy project where we created a noise generator that we mixed with a simple sinus signal. We wanted to prove for ourselves that the trained model is able to detect spikes in the signal and give an alert in that case. Later we could utilize the gained knowledge in working with more complex unstructured data processing, as our AI-enhanced web crawler.