ML Algorithms and Models

- Overview

Machine learning (ML) involves the use of ML algorithms and models. ML algorithms are procedures that run on datasets to recognize patterns and rules. ML models are the output of the algorithm. Models act like a program that can be run on data to make predictions.

Simply put, a ML algorithm is like a recipe that allows computers to learn and predict based on data. Rather than explicitly telling the computer what to do, we feed it large amounts of data and let it discover patterns, relationships, and insights on its own. 

ML algorithms are sets of rules or processes used by an AI system to perform tasks. These tasks often involve discovering new data insights and patterns, or predicting output values from a given set of input variables. 

Some applications of ML include: 

• Image recognition
• Speech recognition
• Recommender systems
• Fraud detection
• Self driving cars
• Medical diagnosis
• Stock market trading
• Virtual try on

- Machine Learning Algorithms

The goal of ML algorithms is to perform pattern recognition in order to learn from data to build ML models. There are many different types of ML algorithms, depending on the goals of your ML project, how data is fed into the algorithm, and how you want the algorithm to "learn."

ML algorithms are the brains behind any model, allowing machines to learn, making them smarter. The way these algorithms work is that they are fed an initial batch of data and, over time, additional data is fed as the algorithm improves its accuracy. 

This process of regularly exposing algorithms to new data and experiences increases the overall efficiency of the machine.

Here are some ML algorithms:

• Reinforcement learning: Helps software agents and machines automatically evaluate the best behavior in a given environment.
• Supervised learning: Provides the model with labeled data to train on. The model learns how to make correct predictions.
• Semi-supervised learning: Uses a combination of labeled and unlabeled data sets during the training period.

• Unsupervised learning: Learns the underlying structure of a dataset without being provided a target variable. 
• Deep learning: Uses different layers of non-linear processing units for feature extraction.

When choosing a ML algorithm, you can consider:

• Your project goal
• Your data's size, processing, and annotation requirements
• The speed and training time
• Your data's linearity
• The number of features and parameters

To assess the performance of ML algorithms, it is essential to establish evaluation criteria. These criteria typically include accuracy, precision, recall, F1-score, training time, model complexity, and interpretability.

- Machine Learning Models

A ML model is a program that uses computational methods to make predictions or find patterns in a dataset. ML models are mathematical representations of the output of the training process. 

ML models are built using supervised ML algorithms that use labeled, unlabeled, or mixed data. They are similar to mathematical functions, taking input data, making a prediction, and serving a response. 

ML models are different from rule-based programs because they don't need to be explicitly coded and can change over time as new data enters the system.  

Here are some steps for implementing a basic ML algorithm:

• Define the problem and gather data
• Preprocess and explore the data
• Split the data into training and testing sets
• Choose a basic ML algorithm
• Train the model
• Deploy the model

[The University of Chicago]

- Model Training

Model training is a stage in the data science development lifecycle. It's the process of running a ML algorithm on a dataset, and then optimizing the algorithm to find certain patterns or outputs. 

Model training involves learning good values for all the weights and bias from labeled examples. The resulting function with rules and data structures is called the trained ML model. 

The process of training ML models can be divided into four steps:

• Data set split for training and evaluation
• Algorithm selection
• Hyperparameter tuning
• Model training

The model's performance during training will eventually determine how well it will work when it is eventually put into an application for the end-users. 

Before training your model, you can:

• Identify the problem and candidate algorithms.
• Identify data required to train the algorithms.
• Collect initial data.
• Identify its quality and suitability for the task.
• Plan what is needed to make the dataset suitable for the project.

- Top ML Algorithms

ML algorithms are processes implemented in code and run on data. The ML model is output by the algorithm and consists of model data and prediction algorithm. ML algorithms provide a type of automated programming in which ML models represent programs.

Here are some ML algorithms:

• K-means clustering: A clustering algorithm that groups similar data points into clusters. The number of groups is called K.
• Reinforcement learning: A machine learning algorithm where a machine learns ideal behavior to maximize its performance.
• Supervised learning: A machine learning algorithm that uses a known dataset to make predictions.
• K-Nearest Neighbor (KNN): A machine learning algorithm that solves classification problems by assigning a new data point to a category.
• Logistic regression: A machine learning classification algorithm that predicts the probability of certain classes based on dependent variables.
• Support Vector Machines (SVMs): A supervised learning algorithm that is used for classification, regression, and outlier detection tasks.
• Naive Bayes: A machine learning algorithm based on the idea of using Bayes' theorem to make predictions.
• Random forest: A supervised learning algorithm that is used for classification and regression.
• Decision tree: A machine learning algorithm for classification and regression problems.

- How to Use ML Algorithms and Models

When a ML algorithm learns from data using one of the ML methods, it builds a ML model. The model is the result of running an algorithm on the data. 

Once you have a model, you can use it to make new predictions on data or similar data sets. Depending on how effectively the algorithm is trained, the model will make predictions with a certain level of accuracy and confidence.

So, what do algorithms and models mean in the context of data science? The goal of ML is to build predictions that can be used to make data-driven decisions for your business.

To do this, you need ML models that can produce high-confidence predictions. The algorithm to produce a model with 90% accuracy is very simple. Training an algorithm to improve accuracy to 95% or higher can be very difficult. When making decisions based on data generated by ML models, a percentage increase in accuracy can make a huge difference.

[More to come ...]