Model-Based vs Instance-Based Learning: Understanding the Differences with Examples
Machine learning is the process of teaching a machine to make decisions and predictions by training it on a large dataset. Two main categories of machine learning are model-based learning and instance-based learning. Both methods have their advantages and disadvantages, and choosing the right method for a particular problem can greatly improve the accuracy of predictions.
In this article, we will explore the differences between model-based and instance-based learning, as well as their advantages and disadvantages, and provide examples of each.
Model-Based Learning
Model-based learning involves creating a mathematical model that can predict outcomes based on input data. The model is trained on a large dataset and then used to make predictions on new data. The model can be thought of as a set of rules that the machine uses to make predictions.
In model-based learning, the training data is used to create a model that can generalize to new data. The model is typically created using statistical algorithms such as linear regression, logistic regression, decision trees, and neural networks. These algorithms use the training data to create a mathematical model that can be used to predict outcomes.
Advantages of Model-Based Learning
Faster predictions: Model-based learning is typically faster than instance-based learning because the model is already created and can be used to make predictions quickly.
More accurate predictions: Model-based learning can often make more accurate predictions than instance-based learning because the model is trained on a large dataset and can generalize to new data.
Better understanding of data: Model-based learning allows you to gain a better understanding of the relationships between input and output variables. This can help identify which variables are most important in making predictions.
Disadvantages of Model-Based Learning
Requires a large dataset: Model-based learning requires a large dataset to train the model. This can be a disadvantage if you have a small dataset.
Requires expert knowledge: Model-based learning requires expert knowledge of statistical algorithms and mathematical modelling. This can be a disadvantage if you don't have the expertise to create the model.
Limited flexibility: Model-based learning can be less flexible than instance-based learning because the model is already created and can't be easily changed.
Example of Model-Based Learning
An example of model-based learning is predicting the price of a house based on its size, number of rooms, location, and other features. In this case, a model could be created using linear regression to predict the price of the house based on these features. The model would be trained on a dataset of house prices and features and then used to make predictions on new data.
Instance-Based Learning
Instance-based learning involves using the entire dataset to make predictions. The machine learns by storing all instances of data and then using these instances to make predictions on new data. The machine compares the new data to the instances it has seen before and uses the closest match to make a prediction.
In instance-based learning, no model is created. Instead, the machine stores all of the training data and uses this data to make predictions on new data. Instance-based learning is often used in pattern recognition, clustering, and anomaly detection.
Advantages of Instance-Based Learning
No need for model creation: Instance-based learning doesn't require creating a model, which can be an advantage if you don't have the expertise to create the model.
Can handle small datasets: Instance-based learning can handle small datasets because it doesn't require a large dataset to create a model.
More flexibility: Instance-based learning can be more flexible than model-based learning because the machine stores all instances of data and can use this data to make predictions.
Disadvantages of Instance-Based Learning
Slower predictions: Instance-based learning is typically slower than model-based learning because the machine has to compare the new data to all instances of data in order to make a prediction.
Less accurate predictions: Instance-based learning can often make less accurate predictions than model-based learning because it doesn't have a mathematical model to generalize from.
Limited understanding of data: Instance-based learning doesn't provide as much insight into the relationships between input and output variables as model-based learning does.
Example of Instance-Based Learning
An example of instance-based learning is the k-nearest neighbour algorithm. This algorithm involves storing all instances of data and then using the closest k instances to make a prediction. For example, in a classification problem where the goal is to predict the species of a flower based on its petal length and width, the k-nearest neighbour algorithm would store all instances of flowers along with their species and petal length and width measurements. When a new flower is presented, the algorithm would find the k closest instances based on their petal length and width measurements and then assign the species of the majority of those k instances to the new flower.
Conclusion
In summary, both model-based and instance-based learning have their advantages and disadvantages, and choosing the right method for a particular problem depends on the size of the dataset, the complexity of the problem, and the expertise of the person creating the model. Model-based learning is typically faster and more accurate than instance-based learning but requires a large dataset and expert knowledge of statistical algorithms and mathematical modelling. Instance-based learning is more flexible and can handle small datasets, but is slower and can make less accurate predictions. By understanding the differences between these two methods, machine learning practitioners can choose the method that is best suited for their specific problem. Hope you got value out of this article. Subscribe to the newsletter to get more such blogs.
Thanks :)