Deep Learning and AI

Machine Learning System vs Rule Based System and the Hybrid Approach

December 8, 2023 • 12 min read


Rule Based System vs. ML Based System

Intelligent systems have revolutionized decision-making across various industries, transforming the way organizations address complex challenges. Choosing the right approach among Rule Based Systems, ML Based Systems, and the hybridized Rule Based Machine Learning (RBML) is crucial for developing effective and efficient intelligent systems.

Rule Based Systems rely on explicit rules defined by domain experts, guiding decision-making in a manner similar to decision trees and IF-THEN statements. On the other hand, ML Based Systems use machine learning algorithms to autonomously learn patterns from data, making them well-suited for handling complex and unstructured information. A Hybrid System combines the strengths of both approaches, integrating human expertise and learning capabilities to address a broad spectrum of challenges.

In this article, we will delve into the characteristics, advantages, and limitations of Rule Based Systems, ML Based Systems, and Hybridized Systems. By using real-world examples and providing considerations for system selection, we aim to offer insights that empower decision-makers to build intelligent systems that foster success and innovation.

Rule Based Systems

Rule Based Systems, also referred to as expert systems, are intelligent systems designed to make decisions or carry out tasks based on predetermined rules. These systems rely on explicit rules crafted by domain experts, typically presented as condition-action pairs. The rules articulate specific conditions or patterns to be identified, and when those conditions are met, corresponding actions or inferences are executed.

In the realm of medical diagnosis, for example, a rule based system could assist doctors in identifying diseases based on symptoms. The system would house a set of rules, such as "IF the patient has a fever AND cough, THEN diagnose with flu." The system deduces the diagnosis when a patient's symptoms align with the specified conditions.

Similarly, in the banking industry, a fraud detection system could be another example. This system would be armed with rules like "IF the transaction amount is unusually high AND occurs in a foreign country, THEN flag as potential fraud." The system applies these rules to incoming transactions and triggers alerts for further investigation whenever the specified conditions are met.

Machine Learning Based Systems

ML Based Systems, or machine learning-based systems, leverage machine learning algorithms to make predictions, decisions, or perform tasks based on patterns learned from data. In contrast to rule based systems, ML based systems do not rely on explicit rules; instead, they learn from examples and data inputs during a training phase.

An illustrative example of an ML Based System is a spam email classifier. Trained on a dataset of labeled emails (spam or non-spam), the system learns patterns and features from the data, extracting characteristics like keywords, email structure, and sender information. This enables it to predict whether a new email is likely spam or not.

While ML Based Systems offer advantages such as handling complex patterns and adapting to new data, they can be perceived as "black boxes" due to the non-explicit decision-making process, making interpretation and explanation challenging. These systems require large amounts of labeled training data, computational resources for model training, and periodic retraining to stay abreast of changing data distributions and evolving patterns.

In image recognition, ML Based Systems excel in developing powerful image classifiers. Training on extensive datasets with labeled images, these systems learn to recognize objects, identify faces, and classify images into different categories.

Language translation systems, such as neural machine translation models, also exemplify ML Based Systems. These models learn to translate text from one language to another by training on bilingual datasets, capturing complex linguistic patterns and semantic relationships for accurate translations.

In fraud detection, ML Based Systems have proven highly effective. Analyzing large volumes of transactional data, these systems identify patterns indicative of fraudulent activities, allowing organizations to detect and prevent financial losses. Learning from historical fraud cases, ML models distinguish between legitimate and fraudulent transactions based on features like transaction amount, location, time, and customer behavior.

By training on labeled datasets containing known fraud instances, ML Based Systems develop sophisticated models that can accurately flag suspicious transactions in real time. ML algorithms adapt to evolving fraud patterns, detecting anomalies not captured by rule based systems. Continuous learning and updates based on new data ensure effectiveness in the ever-changing landscape of fraudulent activities. Additionally, ML Based Systems reduce false positives by fine-tuning model thresholds and incorporating feedback from fraud analysts, enhancing the efficiency and effectiveness of fraud detection processes.

Hybrid - Rule Based Machine Learning Systems

RBML Systems are a fusion of a rule based and ML based approaches, harnessing the defined decision making of rule based systems and the adaptability of machine learning models. A hybridized RBML systems have gained significant traction, particularly in critical domains like fraud detection, where the collaboration of human intelligence and advanced algorithms is pivotal.

Using the same example in a Fraud Detection, hybrid systems excel by leveraging the both rule based components and ML models. The rule based component rapidly identifies transactions of obvious signs of fraud, serving as an initial filter. Then the flexible machine learning component of the hybrid RBML systems will address advanced fraud tactics, not explicitly captured by rule based systems, adding an extra layer of defense.

In practice, hybrid systems operate synergistically. Transactions initially undergo scrutiny by the rule based component, efficiently flagging obvious instances of fraud. For transactions that pass the rule based stage but still raise suspicions, the ML component further scrutinizes them. This integration allows for a comprehensive and dynamic assessment, combining the interpretability of rule based systems with the intricate pattern recognition of ML models. If both Rule Based and ML based models agree, then the detection of a fraud is true. The second line of defense occurs when the two models disagree. For fraud detection, it is better safe than sorry, so flagging the transaction as fraud when the two models disagree is safer in the long run.

1 = Flag as Fraudulent

0= Flag as Valid

Rule Base System = 1

Rule Base System = 0

ML System = 1

Fraudulent Transaction

Fraudulent Transaction

ML System = 0

Fraudulent Transaction

Valid Transaction

The amalgamation of rule based and ML based approaches in hybrid systems offers numerous advantages. It leverages the transparency and interpretability of rule based systems, providing tangible insights into decision-making processes. Simultaneously, the ML component empowers the system to handle complex fraud patterns and adapt to emerging threats and bring to light new potential methods of attack. The collaboration between human expertise and machine learning capabilities in hybrid systems enhances fraud detection accuracy, reduces false positives, and improves overall operational efficiency while educating fraud teams to address novel fraudulent methods.

System Comparison and Contrast

In this section, we will dive deeper into the differences between both Rule based and ML based systems and their differences in domain performance, scalability, adaptability, and precision.


Rule based System

Machine Learning Based System

Domain Performance

Defined Conditions and Explicit Rulings

Complex Conditions, Unstructured Rulings


Limited in Number of Rules and Parameter Size Complexity

Limited in Computational Resources


Not adaptable until updated manually through code

Highly adaptable with iterative training


Far less false positives, but potential for weak points where rules are not set in place.

Highly accurate given high-quality data but has increased chance for false positive if fed noisy data.


Poor recall due to the manual nature of adding additional rules and conditions

Higher recall potential by learning anomalies not explicit in a rule based system.

  • Domain Performance
    • Rule based systems are well-suited for problems with well-defined conditions and explicit rules. Think of it in the manner of IF and ELSE conditions. Where if a certain event occurs, do a specific action. This results in them being more effective in domains where domain experts possess extensive knowledge and can encode rules based on known patterns.
    • ML based systems excel in handling complex patterns and unstructured data. They are particularly useful when explicit rules are not known or when patterns are not easily captured by predefined rules. By training it on high quality data, it can make predictions to a degree of confidence and accuracy without explicit instructions to do so.
  • Scalability
    • In terms of scalability, rule based systems can be limited when the number of rules becomes too large or when handling complex, evolving domains. These rule trees and conditions can get jumbled, messy, and complicated which can possibly lead to errors and unintended results. However, every system will be bound to a specific rule set, so
    • ML based systems can handle large datasets and complex problems, but additional computational resources may be required. Training a machine learning model and enabling it to make its own predictions necessitates high performance hardware for crunching extensive amounts of data, mathematical calculations, and run predicitons.
  • Adaptability
    • Rule based systems require manual updates to incorporate new rules or conditions require more human intervention. Unknown problems can bypass a rule based system causing unintended results and exploits.
    • ML based systems require iterative training that can be baked into the system, requiring less human intervention. While these systems require the training, an unintended result can be fed back to the system to identify adverse behaviors and flag them the next time around.
  • Precision
    • Rule Based Systems tend to have high precision as they rely on explicit rules defined by domain experts. The decision process follows specific conditions, resulting in precise actions or inferences. False positives are less likely since the rules are designed to capture specific patterns or conditions. 
    • While ML Based Systems may have varying precision and can achieve high precision, dependoing on the quality of the training data representing true data. ML models learn patterns from data, and if the training data contains noise or biases, it has a lower precision due to the possibility of false positives.
  • Recall
    • Rule Based Systems may have limitations in the recall when compared to ML systems. If a rule does not explicitly cover a particular scenario, it may fail to recognize related instances. The system's recall is dependent on the comprehensiveness and accuracy of the predefined rules.
    • ML Based Systems generally have higher recall potential. They can learn from a large volume of data, capturing various patterns and exhibiting the ability to recognize complex relationships. This enables ML models to identify anomalies and recognize patterns that may not be explicitly defined in the rules of a rule based system, resulting in higher recall.

 It is worth mentioning that hybrid RBML Systems offer a unique advantage by combining and leveraging the strengths of both Rule Based Systems and ML Based Systems. This blending of approaches allows hybrid systems to mix and match the pros of each system, resulting in enhanced precision and recall capabilities.

Rule based or ML based, Choosing the Right Approach 

When it comes to which system to choose, multiple factors do play a role. When choosing the perfect model, take into account the complexity of the problem you are trying to solve. If the problem has well-defined conditions and rules, a rule based approach might be suitable. On the other hand, if you're dealing with complex patterns or unstructured data, an ML based approach could be more effective in capturing those intricacies.

Second of all, evaluate the availability and quality of your data. Remember that the ML based approach does require substantial amounts of labeled data for the training process, so it's important to ensure that you have enough relevant data to train your models effectively. On the other hand, rule based systems rely more on predefined rules and may require domain experts to provide their knowledge and expertise with no data sets required.

Finally, and most importantly, think about your system’s need to adapt to changing conditions or evolving patterns. ML based systems are known for their adaptability, as they can learn from new data and adjust their models accordingly with time. In contrast, rule based systems require manual updates to incorporate new rules or conditions, which may be more time consuming and requires continuous human monitoring and such.

Of course, it goes without saying that, in most cases, the best choice would be to use a hybrid system. This system will more than be able to handle all issues faced by the two separate systems.


machine learning


Related Content