# Glossary

## What is Bayesian Logic? Link to heading

Bayesian logic, also known as Bayesian inference or Bayesian reasoning, is a mathematical framework for updating beliefs or probabilities based on new evidence or data. It is named after the 18th-century mathematician and theologian Thomas Bayes, who first formulated the idea.

Bayesian logic involves using prior knowledge or beliefs about the probability of an event or hypothesis, along with new evidence or data, to update the probability of that event or hypothesis. The updated probability is called the posterior probability, and it is calculated using Bayes’ theorem, which states that the posterior probability is proportional to the prior probability times the likelihood of the data given the hypothesis.

Bayesian logic is widely used in various fields, including statistics, machine learning, artificial intelligence, and decision-making. It allows for the incorporation of uncertainty and variability into models and can handle complex data structures and dependencies. Bayesian methods are particularly useful in situations where there is limited data or where the data are noisy or incomplete.

## What is Causal Inference? Link to heading

Causal inference is a subfield of statistics and data analysis that is concerned with understanding the cause-and-effect relationships between variables. It involves trying to determine whether a particular event, intervention, or treatment actually caused a change in an outcome, or whether the observed relationship between the two variables is due to some other factor.

Causal inference techniques are used in many different fields, including medicine, economics, public policy, and social science. They are particularly important in situations where we want to know whether a particular treatment or intervention is effective, or whether a particular policy or program is having the desired impact.

One common technique used in causal inference is randomized controlled trials, which involve randomly assigning participants to different treatment groups and comparing their outcomes. Other techniques include observational studies, quasi-experimental designs, and various statistical models and analyses.

## What is a Regression Model? Link to heading

A regression model is a statistical tool used to analyze the relationship between a dependent variable (often denoted as Y) and one or more independent variables (often denoted as X). The purpose of a regression model is to find the best-fit line or curve that describes the relationship between the variables.

In a linear regression model, the relationship between the dependent variable and independent variable(s) is assumed to be linear, which means the best-fit line will be a straight line. Nonlinear regression models, on the other hand, allow for more complex relationships between variables, and the best-fit line or curve may be a polynomial, logarithmic function, or other nonlinear function.

Regression models are commonly used in various fields, including economics, social sciences, engineering, and medical research, to make predictions or to analyze the impact of changes in one variable on another variable. The quality of the model is often assessed by measuring how closely the predicted values match the actual values in the data set, using metrics such as the root mean squared error or coefficient of determination (R-squared).

## What’s the difference between AI and ML? Link to heading

AI (Artificial Intelligence) and ML (Machine Learning) are two closely related terms, but they are not interchangeable.

AI refers to the broad field of computer science that focuses on creating intelligent machines that can perform tasks that typically require human intelligence, such as speech recognition, decision-making, and natural language processing. AI includes a variety of subfields, including robotics, computer vision, and natural language processing.

ML, on the other hand, is a specific subset of AI that involves training machines to learn from data, without being explicitly programmed. In other words, instead of writing code to tell a machine what to do, we can use algorithms to analyze data and make predictions or decisions based on that data.

In short, AI is the broad concept of creating intelligent machines that can perform a variety of tasks, while ML is a specific technique within AI that involves teaching machines to learn from data.

## How does ML work? Link to heading

ML (Machine Learning) is a subfield of AI (Artificial Intelligence) that involves training machines to learn from data, without being explicitly programmed. The basic idea behind ML is to enable machines to learn patterns and relationships in data, and use these patterns to make predictions or decisions about new data.

The ML process typically involves the following steps:

Data collection: The first step in any ML project is to collect data that can be used to train the machine learning model. The data can come from a variety of sources, such as databases, sensors, or web scraping.

Data preparation: Once the data is collected, it needs to be cleaned and pre-processed to remove any noise or inconsistencies. This might involve tasks such as filtering out irrelevant data, removing duplicates, and converting data into a usable format.

Feature engineering: After the data is cleaned, it needs to be transformed into a format that can be used for training the ML model. This might involve selecting relevant features, scaling or normalizing data, and encoding categorical variables.

Model selection: The next step is to choose an appropriate ML model that can be trained on the data. This could be a simple model such as linear regression, or a more complex model such as a neural network.

Model training: Once the model is selected, it needs to be trained on the data using an algorithm that learns from the data and adjusts the model parameters to optimize its performance.

Model evaluation: After the model is trained, it needs to be evaluated on a separate set of data to see how well it performs. This might involve measuring accuracy, precision, recall, or other performance metrics.

Model deployment: If the model performs well on the evaluation data, it can be deployed in a real-world application to make predictions or decisions based on new data.

Overall, ML involves a combination of statistical analysis, optimization algorithms, and computer science techniques to enable machines to learn from data and make predictions or decisions based on that learning.

## What is a neural network? Link to heading

A neural network is a type of machine learning algorithm that is inspired by the structure and function of the human brain. It is a set of interconnected processing nodes, or “neurons,” that work together to learn patterns and relationships in data.

The basic idea behind a neural network is to feed input data into the network, which then processes the data through a series of interconnected layers of neurons. Each neuron receives input from other neurons in the previous layer, applies a mathematical function to that input, and passes the result to the next layer of neurons.

Neural networks can be used for a variety of tasks, such as image and speech recognition, natural language processing, and prediction. They are especially useful for tasks that involve complex patterns and relationships in data that may be difficult to capture using traditional machine learning algorithms.

Neural networks can be trained using a process called backpropagation, which involves adjusting the weights and biases of the neurons in the network to minimize the difference between the predicted output and the actual output. This process is repeated many times until the network’s performance on the training data reaches a desired level of accuracy.

Overall, neural networks are a powerful tool for machine learning, and have been used to achieve state-of-the-art performance on a wide range of tasks.

## What is Deep Learning? Link to heading

Deep learning is a subset of neural networks. Neural networks are a class of algorithms modeled after the structure and function of the human brain, consisting of interconnected nodes or “neurons” that process and transmit information. Deep learning involves training artificial neural networks with many layers, allowing them to learn and recognize complex patterns in data.

So, the main difference between deep learning and neural networks is the number of layers in the network. A neural network with only a few layers is often referred to as a “shallow” network, while a neural network with many layers is considered a “deep” network.

While neural networks can be used to solve a variety of problems, they may not always be able to handle complex data patterns. In contrast, deep learning is particularly well-suited for handling large, complex datasets, and has shown great success in a wide range of applications, including image and speech recognition, natural language processing, and more.

In summary, neural networks refer to a broader class of algorithms that include deep learning, while deep learning is a specific type of neural network that involves many layers of nodes.

## What is Natural Language Processing? Link to heading

Natural Language Processing (NLP) is a field of computer science and artificial intelligence that deals with the interaction between computers and human language. It involves programming computers to understand, interpret, and generate natural language.

NLP can be used for a variety of tasks, including language translation, sentiment analysis, text classification, speech recognition, and language generation. It involves combining techniques from computer science, linguistics, and statistics to develop algorithms and models that can process and analyze large volumes of text data.

NLP can be a complex field due to the nuances of human language, such as sarcasm, ambiguity, and context-dependence. Therefore, it requires a deep understanding of language and a broad range of techniques to achieve accurate and meaningful results.

## What is Computer Vision? Link to heading

Computer vision is a field of artificial intelligence and computer science that focuses on enabling machines to interpret and understand visual information from the world around them, including images and videos. It involves developing algorithms and techniques that allow computers to extract useful information from visual data and use it to perform various tasks, such as object recognition, scene reconstruction, motion analysis, and more.

Computer vision is a critical technology in many areas, including autonomous vehicles, robotics, medical imaging, security and surveillance, and more. It involves a combination of techniques from computer science, mathematics, physics, and neuroscience, and has a wide range of applications in both industry and research.

## What is a Monte Carlo Simulation? Link to heading

Monte Carlo simulation is a computational technique that uses random sampling and statistical analysis to model and analyze complex systems. It is a method for estimating the probability distribution of outcomes for a given system by generating random samples of possible inputs and calculating the corresponding outputs.

The technique is named after the famous Monte Carlo Casino in Monaco, which is known for its gambling games that involve random events. In a Monte Carlo simulation, the inputs to the system are chosen randomly, and the corresponding outputs are computed based on the system’s mathematical model. This process is repeated many times to generate a large number of possible outcomes.

The results of the Monte Carlo simulation can then be used to estimate the probability distribution of various outcomes, such as the likelihood of a particular investment strategy achieving a certain return, or the expected value of a complex engineering project. Monte Carlo simulations are commonly used in finance, engineering, and scientific research to model complex systems that are difficult or impossible to solve analytically.

## What is Sensitivity Analysis? Link to heading

Sensitivity analysis is a method used to determine how variations in the input variables of a model affect the output of the model. The goal of sensitivity analysis is to identify which input variables are the most important and have the greatest impact on the output of the model, and which input variables have less impact.

Sensitivity analysis is commonly used in fields such as engineering, finance, and environmental modelling. It involves changing one input variable at a time, while holding all other variables constant, and observing how the output of the model changes in response. Sensitivity analysis can be used to identify the key drivers of a model, to test the robustness of the model, to assess the reliability of the model, and to optimise the model.

Sensitivity analysis can be performed using a variety of methods, including one-factor-at-a-time analysis, factorial design, and Monte Carlo simulation. The choice of method depends on the complexity of the model and the resources available for the analysis.

## What is Soft Operational Research? Link to heading

Soft Operational Research (SOR) is an approach to operational research (OR) that emphasises the importance of the social, human, and organisational aspects of problem-solving. It is a methodology that recognizes that complex problems cannot be fully understood or solved by mathematical models alone and requires an interdisciplinary approach to problem-solving that includes both hard and soft systems thinking.

The main focus of SOR is on understanding the subjective and often intangible aspects of a problem, such as human behaviour, social structures, and cultural norms. It involves the use of qualitative research methods such as ethnography, case studies, and participatory approaches to elicit the perspectives and experiences of stakeholders and to co-create solutions.

The aim of SOR is to enable decision-makers to better understand complex problems and to design effective and sustainable solutions that take into account the diverse and often conflicting interests of stakeholders. By incorporating the human and social dimensions of problem-solving, SOR can help to create more inclusive and socially just outcomes.