Anomaly detection in machine learning

Detecting aberrant data, or outliers, in bigger data sets with possible insights into company activity is vital for uncovering inefficiencies, infrequent events, the core cause of difficulties, or operational improvements. What is an anomaly and why is detection important?

Anomalies differ by company and function. Definition of “normal” patterns and metrics based on business operations and goals and identification of data points outside of an operation’s typical behavior is anomaly detection. For instance, heavy website or app traffic for a certain period may indicate a cybersecurity threat, therefore you’d want a system that instantly warns you to fraud. It could also indicate a successful marketing campaign. Knowing and interpreting anomalies and having data to contextualize them is crucial to understanding and safeguarding your business.

IT departments working in data science must make sense of growing and changing data. This blog will discuss how machine learning and artificial intelligence are used to detect abnormal activity using supervised, unsupervised, and semi-supervised methods.

Supervised learning

Supervised learning detects anomalies using real-world input and output data. These anomaly detection systems require data analysts to categorize data points as normal or abnormal for training. A machine learning model trained with labeled data may identify outliers from examples. This type of machine learning can detect known outliers but not unexpected abnormalities or future difficulties.

Common supervised machine learning algorithms:

KNN algorithm: This anomaly detection approach uses density-based classifiers or regression modeling. Regression modeling determines the link between labeled and variable data. The idea is that similar data points will be close together. Anomalies occur when data points are farther from dense sections.

LOF: Local outlier factor KNN and local outlier factor are density-based algorithms. KNN develops assumptions based on data points closest together, while LOF draws conclusions from data points farthest apart.

Unsupervised learning

Unsupervised learning can handle complex data sets without labels. Unsupervised learning uses deep learning and neural networks or auto encoders that replicate biological neuron signals. These strong techniques may identify patterns in raw data and assume normality.

These methods can help find anomalies and reduce laborious combing through enormous data sets. However, data scientists should monitor unsupervised learning outputs. Because these methods make assumptions about incoming data, they may mislabel abnormalities.

For unstructured data, machine learning algorithms include:

K-means: This data visualization technology clusters comparable data points using a mathematical equation. Means, or average data, are the cluster center points that all other data is associated to. Data analysis can reveal patterns and insights from unusual data using these clusters.

Isolation forest: The isolation forest algorithm detects anomalies using unsupervised data. Unlike supervised anomaly detection, which starts with labeled normal data points, this method isolates abnormalities first. Like a “random forest,” it builds “decision trees” that map data points and randomly select a region to study. Repeating this method gives each point an anomaly score between 0 and 1 based on its proximity to the others; values below.5 are regarded typical, but levels above that threshold are odd. Scikit-learn, a free Python machine learning package, has isolation forest models.

One-class support vector machine (SVM): This anomaly detection method defines normality using training data. Clusters within the defined borders are typical, whereas those outside are abnormalities.

Semi-supervised learning

Semi-supervised anomaly detection approaches combine the benefits of the preceding two. Engineers can automate feature learning and work with unstructured data using unsupervised learning. By combining it with human supervision, they can monitor and regulate model learning processes. This frequently improves model predictions.

Linear regression: This predictive machine learning tool uses dependent and independent variables. Using statistical equations, the dependent variable is calculated from the independent variable. When just some information is known, these equations predict future outcomes using labeled and unlabeled data.

Use scenarios for anomaly detection

Anomaly detection helps businesses across industries perform. Data type and operational challenge determine the employment of supervised, unsupervised, and semi-supervised learning techniques. Use cases for anomaly detection include:

Supervised learning applications:

Retail

Labeled data from last year’s sales can anticipate future goals. It can also set sales personnel benchmarks based on prior performance and company needs. Patterns can reveal product, marketing, and seasonality as all sales data is known.

A weather forecast

Using historical data, supervised learning algorithms can forecast weather trends. Recent barometric pressure, temperature, and wind speed data helps meteorologists make more accurate forecasts that account for changing conditions.

Unsupervised learning is use cases

Intrusion detection system

These software or hardware devices monitor network traffic for security breaches or criminal behavior. Machine learning algorithms can detect real-time network threats, protecting user data and system functioning.

These algorithms can visualize typical performance using time series data, which analyzes data points at defined intervals throughout time. Network traffic spikes or unusual patterns can be highlighted as security risks.

Manufacturing

Manufacturing products, optimizing quality assurance, and managing supply networks require effective machinery operation. Unsupervised learning systems can forecast equipment failures using unlabeled sensor data. Companies can fix before a severe breakdown, decreasing equipment downtime.

Medical application cases for semi-supervised learning

Medical

Medical experts can categorize diseased photographs using machine learning techniques. However, visuals differ from person to person, making it impossible to categorize all potential issues. Once trained, these algorithms can process patient data, infer from unlabeled photos, and identify issues.

Fraud detection

Predictive algorithms can detect fraud using semi-supervised learning using labeled and unlabeled data. Labeled credit card transactions can reveal strange purchasing trends.

Fraud detection solutions can also make inferences based on user activity, such as location, log-in device, and other unlabeled data.

Observability in anomaly detection

Tools that make performance data more visible enhance anomaly detection. These tools assist prevent and fix abnormalities by identifying them immediately. IBM Instana Observability uses AI and machine learning to provide team members with a comprehensive performance data view, enabling mistake prediction and proactive troubleshooting.

IBM Watsonx.ai is a strong generative AI tool that can analyze massive data sets and provide valuable insights. IBM Watson.ai can quickly and thoroughly analyze data to find patterns and trends that can be used to spot anomalies and anticipate future outliers. Watson.ai serves several business needs across industries.