Introduction to Anomaly Detection using PyCaret

Businesses are continuously hunting for new techniques to assist in streamlining their business operations in today's competitive environment. Utilising an anomaly detection algorithm is a great place to start.

Industries such as finance, retail, utilities and manufacturing are continuously hunting for new techniques to assist in streamlining their business operations in today's competitive environment. These industries generate streams of data and frequently have systems and experts in place to track key business operations. Within one organization, for example, an IT department could be monitoring systems performance, while the security team may be monitoring anti-money laundering (AML). 

Anomalies in one area generally have some impact on performance in other areas, but making the connection is difficult when all departments operate independently. Furthermore, because most accessible tools for this sort of monitoring focus on historical events, there is a built-in lag between significant events  and when it may (or may not) be detected. Every event that is uncovered might be a chance to save money, stop a fraud, or refine a process.

AI has the ability to spot patterns and trends in data that are beyond human scale, with greater precision, less bias and increased accuracy. In this article, we will be diving into the basics of anomaly detection, its types, methods, and why anomaly detection is critical for businesses. Finally, we will be looking at a simple and tutorial-styled implementation of anomaly detection in PyCaret. The article is divided into the following sections:

  1. What is Anomaly Detection?
  2. Anomalies in Data
  3. Anomaly Detection Techniques
  4. Anomaly Detection for businesses
  5. Implementation of anomaly detection in PyCaret

What is Anomaly Detection?

Procedures that detect spurious points in data; highlighting data that do not match expected values, are known as anomaly detection. These anomalies might indicate unexpected network activity, reveal a malfunctioning sensor, or simply highlight areas for  investigation. 

It is vital for people to be able to recognize changes in performance and act on this knowledge. A change in a measure might be harmless, or it could signal a negative occurrence in the firm, or it could signal a great chance for growth. Users may distinguish between inconsequential changes and those that are important by being notified of these situations via anomaly detection, which leads to insight and action. A well-designed anomaly detection algorithm that learns from a specific organization, for specific data, allows humans to focus on what actually matters rather than constantly monitoring changes around the clock.

Anomaly detection is often a manual process and is conducted primarily by human-in-the-loop in data-poor industries. Because there are just a few high-level variables to measure, members of the analytics team use data extracted from operational systems to manage them. 

Scalability arises as an issue as firms develop and become more data rich. Tracking must now be more specific — for example, tracking "overall" sales used to suffice, but today monitoring sales by category and nation is regarded as crucial in determining the organization's performance.

With hundreds, thousands, or even millions of indicators to keep track of, human operators struggle to keep up with a “firehose” of data and dealing with this additional complexity becomes both time-consuming and costly.  Monitoring dashboards have attempted to meet this problem, but corporations now have hundreds of dashboards, each with reams of graphs, that are still relying on human operators to sift through and review them- this is just not a viable long term solution.

Anomalies in Data

Although anomalies in data are categorized by people differently according to the context in which one is defining an anomaly. For instance, a variation is a dataset that can be considered an anomaly for some and can be normal behavior for others. But, from a data-driven technical point of view, anomalies can be classified into three types:

Update Anomalies occur when the person in charge of maintaining all of the records up to date and correct is asked to modify an employee's title owing to a promotion, for example. There will be many titles linked with the employee if the data is stored redundantly in the same table and the worker misses any of them. There is no way for the end user to tell which title is right.

Insertion anomalies occur when critical data cannot be inserted into the database because other data is missing. An insert anomaly occurs when a system is built to demand that a client be on file before a transaction can be made to that customer, yet you cannot add a customer until they have purchased anything. It is a typical case of "catch-22."

Deletion anomalies occur when the deletion of undesired data results in the deletion of desired data as well. If a single database record contains information about a specific product as well as information about a company's salesperson, and the salesperson leaves, the product information is removed along with the salesperson's information.

Anomaly Detection Techniques

Machine learning has provided us with extensive ways for anomaly detection. This is a procedure that is often carried out with the use of statistics and machine learning. The reason for this is that most businesses that require outlier identification nowadays operate with massive volumes of data, such as transactions, text, picture, video material, and so on. It would take days to go through all of the changes that occur within a bank every hour, and more are created every second. Manually extracting any relevant insights from this volume of data is simply impossible.

To gather, clean, arrange, analyze, and store data, you will need technologies that are not afraid of copious amounts of information. When big data sets are involved, machine learning approaches produce the greatest outcomes. Machine learning algorithms can handle a wide range of data. You may also select an algorithm based on your situation and mix several strategies to achieve the best results. Machine learning in real-world applications helps to speed up the anomaly detection process and save resources. It can happen both after the fact and in real time. In fraud detection and cybersecurity, for example, real-time anomaly detection is used to increase security and resilience.

The three main techniques of machine learning-driven anomaly detection include supervised, unsupervised, and semi-supervised anomaly detection.

Supervised anomaly detection

A training dataset is required for supervised anomaly identification by an ML engineer. The dataset's items are divided into two groups: normal and aberrant. These samples will be used by the algorithm to extract patterns and discover anomalous patterns in previously unknown data. In supervised learning, the training dataset's quality is critical. Because someone must gather and name examples, there is a lot of physical labor required.

Unsupervised anomaly detection

The most prevalent kind of anomaly detection is unsupervised methods, and neural networks are the most well-known example. 

Artificial neural networks reduce the amount of human effort required to pre-process examples by eliminating the requirement for manual labelling. Even unstructured data may be used with neural networks. NNs can spot irregularities in unlabeled data and apply what they have learnt to fresh data.

The benefit of this strategy is that it reduces the amount of manual effort involved in anomaly detection. Furthermore, it is sometimes hard to anticipate all of the potential abnormalities in a dataset. Take, for example, self-driving automobiles. They may be confronted with a circumstance on the road that they have never encountered before. It would be hard to categorize all road scenarios into a limited number of categories. That is why, when working with real-time data, neural networks are invaluable.

Semi-supervised anomaly detection

The advantages of the preceding two approaches are combined in semi-supervised anomaly detection methods. Unsupervised learning methods may be used to automate feature learning and deal with unstructured data by engineers. They can, however, monitor and manage what kinds of patterns the model learns by integrating it with human supervision. This generally improves the accuracy of the model's predictions.

Anomaly Detection for businesses

Finding patterns of interest (outliers, exceptions, quirks, and so on) that differ from anticipated behavior within a dataset is what anomaly detection is all about. The end game  or outcome of anomaly detection, like other data science initiatives, is not merely an algorithm or a functional model. Instead, it is about the value of the information provided by outliers. That is, money saved through averting equipment damage, money wasted on fraudulent transactions, and so on for a firm. It might imply earlier detection or simpler treatment in health care.

A large-scale business event detection system in an ideal world would use a comprehensive approach to anomaly identification and do so in real time. Real-time monitoring and analysis of these data patterns can aid in the detection of subtle – and not-so-subtle – and unanticipated changes whose fundamental causes require further research.

If an anomaly detection system is not oriented to make sense of the vast stream of metrics as a business expands, increased occurrences may go missing. Although not every measure is linked to money, the majority of them are. Most businesses nowadays use manual identification of abnormal situations by constructing several dashboards and monitoring daily or weekly data, or by defining upper and lower alert levels for each indicator. Human error, false positives, and undetected abnormalities are all possibilities with these procedures.

A company may need an anomaly detection algorithm for a number of areas of analytical monitoring.

Monitoring sales performance

Customers have grown to anticipate a flawless flow from visit to purchase completion in eCommerce, yet issues can arise at any point along the way. Failure to address these issues when they (almost always) develop results in a loss of income for the company. Reports on eCommerce funnel activity are frequently given for weekly review, but even a one-day outage may be incredibly costly in terms of lost sales, especially if the issue affects numerous regions of a website.

Monitoring market performance

Every dollar spent, impression, click, and conversion is valuable to marketers. Traditional techniques of analyzing and enhancing marketing performance might take days to weeks to respond to concerns. This will  cause a company to waste money on marketing channels that are not generating optimal returns and leaving income on the table. Performance and analytics teams frequently examine last week's (or month’s, or quarter's) results to see which campaigns were successful in generating conversions, clicks, and impressions. Traditionally given through dashboards, these static evaluations frequently arrive too late to be useful.

Monitoring user experience

An error-free experience is critical for consumer-facing organizations, whether in content streaming, service supply (think Gmail), or social networking. Users are entitled to feel cheated if the service they have paid for does not perform as promised! Leading signs for this would be highlighted via anomaly detection before it became a P1, major issue, allowing the team to make modifications ahead of the crucial event, preserving the customers' trust in the company's core service (and their subscription income with it!).

Anomaly Detection using PyCaret

Now, we move on to a simple implementation of anomaly detection using the PyCaret library, which is an open-source machine learning library for python. You can install PyCaret using the following command.

Let us move on to the implementation. The dataset used in this tutorial can be found here.


Anomaly detection is an increasingly useful technique for industries faced with increasingly vast and heterogeneous data, that operates beyond human ability to spot trends and patterns, let alone act on them. Machine Learning derived  anomaly detection resolves these issues with the ability to spot anomalies and change points in real-time and alerting operations teams for instant response. 

Further, we now have models better able to predict anomalies before they happen, which is a game changer for industries such as oil and gas, where the cost of shutting down a network to  repair a failure is millions of dollars per day, but where releasing  pressure in the network to avoid the failure has negligible cost and no downtime.   



28 January 2022


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