Classification model

See also: Machine learning terms

Introduction

In machine learning, a classification model predicts which class a new input belongs to. In contrast, regression models predict numbers rather than classes.

What is a Classification Model?

Classification models are machine learning algorithms that take input data and predict which class it belongs in. The input usually consists of features or attributes, while the output is a class label. The purpose of a classification model is to develop an algorithm that maps input data onto an accurate class label.

Supervised learning utilizes both input features and their corresponding class labels as training data. The classification model is then trained on this labeled data, then applied to make predictions on new, unseen data.

Types of Classification Models

There are various classification models, such as:

1. Binary classification: These models attempt to predict between two possible classes.
2. Multi-class classification: These models predict between more than two distinct classes.
3. Probabilistic classification: These models estimate the likelihood that an input belongs to each class.
4. Decision tree classification: These models employ a decision tree to classify input data based on an array of decisions.

How Classification Models Work

Classification models work by learning a function that maps input features to an output class label. The specific function used depends on the type of model and training algorithm employed.

In general, a classification model works by first analyzing the training data and recognizing patterns or features indicative of each class. It then uses these patterns to create an algorithm capable of accurately classifying new, unseen data.

Training a model involves providing it with labeled examples and then tweaking its internal parameters to minimize the difference between its predicted output and true output. After training is complete, this new function can be applied to new data by applying what has been learned to input features.

Applications of Classification Models

Classification models have many practical uses, such as:

1. Spam detection: Utilizing a classification model, email content can be classified as either spam or not spam.
2. Credit Risk Assessment: Utilizing a classification model, one can predict an applicant's creditworthiness based on their financial history and other factors.
3. Medical Diagnosis: Utilizing a classification model, medical images or other data can be classified as indicative of an underlying disease or condition.
4. Sentiment Analysis: A classification model can be utilized to categorize social media posts or reviews as positive, negative, or neutral.

Explain Like I'm 5 (ELI5)

Classification models work like teachers who can look at pictures and identify what it is. After years of practice, they've come to recognize patterns in pictures that indicate whether it's of a cat, dog, or bird. When presented with new data sets, classifiers use what they've learned to predict which group it belongs in; for instance, looking at information about someone could potentially predict whether or not they will pay back loans.