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Supervised Learning - A Complete Introduction

What is Supervised Learning in Artificial Intelligence?

Supervised learning, also called supervised machine learning, is a subset of artificial intelligence (AI) and machine learning. The goal of supervised learning is to understand data within the context of a particular question.

Supervised learning involves using labeled datasets to train computer algorithms for a particular output. As the user feeds input data to the model, the system adjusts to predict outcomes and classify data more accurately by cross validating—adjusting its weights to more closely fit the model.

Collecting labeled training data is the first step in the AI supervised learning process. With sufficient data available, splitting this labeled data into three sets is the next step: training, validation, and testing. The supervised learning algorithm minimizes errors in the model with the training set. Users can verify the learning algorithm’s progress independently with the validation set. The test set offers real world test data only to be used when the validation set proves the model is optimal and can generalize to new data.

Supervised learning vs unsupervised learning charts - how supervised machine learning compares to unsupervised machine learning.
Image from Informatec.

 

What’s the Difference Between Supervised and Unsupervised Learning?

Unsupervised machine learning and supervised machine learning are frequently discussed together. We explained how supervised learning works above. The primary difference between supervised vs unsupervised learning is that unsupervised learning uses unlabeled data. From that data, it identifies patterns that help solve association problems or clustering in supervised learning.

This is especially helpful when a supervised learning data set presents experts with confusing or unclear common properties. Common clustering algorithms are k-means, hierarchical, and Gaussian mixture models.

Here are some of the more common supervised and unsupervised learning techniques in data mining.

Supervised learning teaches the computer by example. This is also how it makes predictions; it learns from past data and uses its new knowledge to predict future events and process present data.

Labeled AI supervised learning examples provide the system what it needs to learn. The input data is tagged or labeled as the correct answer to ensure accurate predictions.

All supervised learning algorithms are basically complicated algorithms that are either classification or regression models.

Supervised learning classification models predict the category of the data where the output variable can be categorized—for example, “Yes or No”, or “0 or 1.” These classification models are used for scorecard prediction of exams, sentiment analysis, spam detection, time series data classification, and other real-world applications.

Machine learning supervised regression models are a common method most often used for problems where the output variable is a real value such as dollars, a unique number, pressure, salary, or weight, for example. The most common supervised regression models include polynomial regression, logistic regression, linear regression, and ridge regression.

Practical, real life applications include:

Unsupervised learning, in contrast, trains machines to use unlabeled, unclassified data so the machine learns to classify the data by itself without any prior information. The aim is to expose machines to such massive volumes of different data that they identify hidden patterns and gain new insights. This is why unsupervised learning algorithms lack defined outcomes and instead determine what is interesting or different from the given dataset for supervised learning.

Although clustering is an example of supervised learning, it is also one of the most common unsupervised learning methods, involving organizing unlabelled data items into clusters of similar items. The main goal is to identify similarities in the data points and group similar data points  into a cluster.

Anomaly detection is the identification of rare or anomalous events, items, or observations which significantly differ from the majority of the data. These data outliers are generally suspicious and anomaly detection is frequently part of medical error and bank fraud detection.

Who uses unsupervised learning? Practical applications of unsupervised learning algorithms include:

 Each of these supervised and unsupervised learning methods should be considered in context. There are advantages and disadvantages of supervised learning techniques even for appropriate applications.

Unsupervised learning is a kind of step between supervised learning and deep learning (discussed below).

Semi-supervised learning, also called partially supervised learning, is a machine learning approach that combines a large amount of unlabeled data with a small amount of labeled data during training.

Weak supervision in machine learning is a part of machine learning where imprecise or unorganized data are used to label unsupervised data to use more massive amounts of data in supervised learning or other forms of machine learning.

Both of these techniques combine supervised and unsupervised learning in some sense.

Advantages and Disadvantages of Supervised and Unsupervised Learning

Although supervised learning may offer many advantages, such as improved automation, deep data insights, and the others listed above, the challenges of developing sustainable models include:

  • Datasets for supervised learning can result in algorithms learning incorrectly because they have a higher likelihood of human error
  • Accurate structuring of these types of models demands expertise
  • Training the models can be time intensive
  • Unlike unsupervised learning models, which classify data and cluster on their own, supervised learning models cannot function without supervision

Which is better

Which machine learning technique is best for which problem depends on a number of factors. In general, it pays to take a deliberate approach when making a decision.

Evaluate the data to determine whether it is mostly labeled or unlabelled, and if it is unlabeled, whether additional labeling is supported by existing expert knowledge. These factors help determine whether a supervised, semi-supervised, unsupervised, or reinforced approach might be best.

Define the problem and goal; are there defined, recurring questions or will algorithms need to predict new problems? Available algorithms should have the right dimensionality for the problem in terms of number of attributes, features, or characteristics. Candidate algorithms should be suited to the overall structure of the dataset and its volume.

What are Some Supervised Learning Use Cases?

So, when do we use supervised learning? These models can develop and advance various applications, including:

  • Customer sentiment analysis. Supervised machine learning algorithms can help organizations identify and characterize critical information inside massive amounts of brand sentiment data—providing detail about emotion, context, and intent—with minimal human intervention for enhanced brand engagement efforts.
  • Object- and image-recognition. ML algorithms can help locate, isolate, and classify objects in images and videos.
  • Predictive analytics. Supervised learning models help develop predictive analytics systems to deliver deeper insights into a range of data points. This enables businesses to pivot to benefit the brand, justify decisions, or anticipate results based on specific output variables.
  • Spam detection. Spam detection is a kind of model. Deploying supervised classification algorithms in machine learning, users can effectively train databases to organize spam and non-spam-related correspondence based on patterns or anomalies in new data.
The difference between supervised and unsupervised learning: Diagram of supervised and unsupervised learning techniques in data mining.
Image from Devin Soni via Towards Data Science.

Types of Supervised Machine Learning Algorithms 

Supervised learning teaches models to reach a goal output using a training set. This training dataset includes correct outputs as well as inputs, both of which allow the model to learn continuously as the algorithm uses the loss function to measure its accuracy, adjusting to minimize error.

As an introduction to supervised machine learning, there are two types of data mining problems—classification and regression:

  • Classification assigns test data into specific categories accurately using an algorithm. Common classification algorithms are decision trees, k-nearest neighbor, linear classifiers, random forests, and support vector machines (SVM), described below.
  • Regression explains the relationship between dependent and independent variables and can be used to make projections. Logistic regression, linear regression, and polynomial regression are popular regression algorithms.

Various computation techniques and algorithms are used in supervised learning data science. Some of the most commonly used learning methods that in turn influence the types of learning tasks include:

Neural Networks

Neural networks, leveraged mostly for deep learning algorithms, process training data by mimicking the human brain’s interconnectivity with a mesh of nodes. Each node in a neural network is made up of weights, inputs, a threshold or bias, and an output. Neural networks learn to map through supervised learning, and with the right training can provide the correct answers.

Naive Bayes

Naive Bayes adopts the class conditional independence principle of Bayes Theorem. This means that each predictor affects the result equally, and the presence of one feature does not impact another in the probability of a given outcome. This technique is primarily used in spam identification, text classification, and recommendation system forms of machine learning supervision.

Linear Regression

Linear regression identifies relationships between a dependent variable and one or more independent variables to make predictions about future outcomes. Simple linear regression refers to situations in which there is only one independent variable and one dependent variable; it is referred to as multiple linear regression as the number of independent variables increases. Unlike other regression models, when plotted on a graph, this model remains linear or straight.

Logistic Regression

Logistic regression is selected when the dependent variable is categorical, meaning they have binary outputs, such as "yes" and "no” or "true" and "false". It is used mostly for binary classification problems, such as spam identification, although both regression models seek to understand relationships between data inputs.

Support Vector Machine (SVM)

A support vector machine is a supervised learning model typically used for data classification problems, where a hyperplane known as the decision boundary is used to create maximal distance between two classes of data points.

K-Nearest Neighbor

The K-nearest neighbor algorithm, also called the KNN algorithm, is a non-parametric supervised machine learning model that classifies data points based on their association and proximity to other available data based on the idea that similar data points can be found near each other. It is easy to use but its low calculation time grows with the test dataset; this is why KNN is typically used for supervised learning image recognition and recommendation engines but less appealing for classification tasks.

Random Forests

Random forest is a supervised machine learning algorithm flexible enough for both regression and classification. The "forest" refers to uncorrelated decision tree supervised learning, which groups trees to create more accurate data predictions and reduce variance.

What is Classification in Supervised Learning?

A classification algorithm receives data points during training with an assigned category. Then its task is to assign an input value to a class or category based on the training data.

An obvious example of classification in supervised learning is determining whether an email is spam. This binary classification problem offers two choices: spam, or not spam, and will offer the algorithm emails that are both spam and not spam as training data.

Classification problems depend on the situation and the data. Here are a few popular classification algorithms:

  • Decision Trees
  • K-Nearest Neighbor
  • Linear Classifiers
  • Random Forest
  • Support Vector Machines

Deep Learning vs Supervised Learning

A machine learning technique, deep learning teaches computers to learn by example, something that comes naturally to humans. In deep learning, a computer model learns to execute classification tasks directly from text, images, sound, or other data. Deep learning (DL) techniques represent a major departure from classic machine learning models.

In contrast, supervised learning is the most common form of machine learning. In supervised learning, the training set, a set of examples, is submitted to the system as input. A typical example is an algorithm trained to detect and classify spam emails.

Reinforcement vs Supervised Learning

Reinforcement learning and supervised learning differ as follows. In supervised learning, the model is trained with the correct answer itself because the training data has the answer key. In reinforcement learning, the reinforcement agent must decide how to execute any given task because there is no answer provided.

Why is it important?

Supervised machine learning enables organizations to transform data into actionable insights, promote desired outcomes, and avoid unwanted outcomes for their target variable.

Supervised machine learning is among the most powerful ways businesses can harness AI systems to make decisions more quickly and accurately than humans and solve numerous problems:

What is a Supervised Learning Predictive Model? 

Predictive modeling is part of data analytics mostly used in Artificial Intelligence (AI) and Machine Learning (ML) that uses data mining and probability to make predictions. Predictive modeling employs detection theory along with different analytics, regression algorithms, and statistics to estimate event probability.

There are two general types of predictive modeling: parametric and non-parametric modeling. A learning model that compiles data of a predetermined size with different parameters, independent of the number of training variables is called a parametric model. ML algorithms that instead make assumptions regarding mapping functions are called non-parametric ML algorithms and are a good fit for large amounts of data without previous available knowledge.

How Does Explorium help?

Explorium’s external data management platform and gallery of external data sources empowers business leaders and data scientists across industries such as financial services, insurance, eCommerce, consumer goods, retail, and technology to quickly access supervised learning data to scale different analytics and machine learning use cases across lines of business.

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