Nepedia
Back to Discover
Advanced Reader
🔢

Probability

math Maturity 11-13 Vital Level 3 Next article →

Probability is the mathematical study of how likely an event is to occur. It provides a numerical way to describe uncertainty and the expected frequency of random events. In a mathematical sense, a probability is always a value between 0 and 1. A larger number indicates that an event is more likely to happen. These values are often expressed as percentages, ranging from 0% to 100%.

probability vs odds
probability vs odds

This field allows us to make logical inferences about the world even when we cannot predict individual outcomes with certainty.

There are different ways to calculate these numbers depending on the context. In a purely theoretical setting, such as tossing a coin, we use theoretical probability. This is calculated by taking the number of desired outcomes and dividing it by the total number of all possible outcomes. For example, if you toss a coin twice, there are four possible outcomes: head-head, head-tail, tail-head, and tail-tail. The probability of getting head-head is 1 divided by 4, which is 0.25 or 25%.

Mutually Exclusive and Non-exclusive Probability Events
Mutually Exclusive and Non-exclusive Probability Events

In contrast, empirical probability deals with the results of real-world experiments.

Scholars also debate the fundamental nature of probability through different interpretations. Objectivists believe probability describes a physical or objective state of affairs. One popular version is frequentist probability, which views probability as the relative frequency of an outcome when an experiment is repeated indefinitely. Another version is propensity probability, which suggests an experiment has a tendency to yield a certain result even if it only happens once.

Dice Distribution (bar)
Dice Distribution (bar)

Subjectivists, however, see probability as a measure of a person's degree of belief. The most famous version is Bayesian probability, which combines expert knowledge, called a prior probability distribution, with new experimental data through a likelihood function. This process results in a posterior probability distribution.

While people have used games of chance to explore these ideas for centuries, the formal science is relatively modern. Historically, the word "probable" meant something that was approvable or sensible to hold as an opinion. In the sixteenth century, the Italian polymath Gerolamo Cardano demonstrated how to define odds as a ratio of favorable to unfavorable outcomes.

Cardano
Cardano

Later, in 1657, Christiaan Huygens published one of the first scientific treatments of the subject.

Christiaan Huygens-painting
Christiaan Huygens-painting

By the early 1700s, works by Jakob Bernoulli and Abraham de Moivre helped establish probability as a formal branch of mathematics.

Significant progress was made in understanding errors and distributions during the late 18th and 19th centuries. Pierre-Simon Laplace proposed two important laws of error in 1774 and 1778. His second law describes the frequency of an error as an exponential function of the square of that error. This is known as the normal distribution or the Gauss law.

Bendixen - Carl Friedrich Gauß, 1828
Bendixen - Carl Friedrich Gauß, 1828

While named after Carl Friedrich Gauss, other mathematicians like Adrien-Marie Legendre also contributed to these ideas. The field continued to grow with Andrey Markov introducing Markov chains in 1906 and Andrey Kolmogorov developing modern probability theory based on measure theory in 1931.

Today, probability theory is essential for managing complex systems and making informed decisions. It is used in many professional fields to assess risk and model future events. The insurance industry uses actuarial science to determine pricing and manage financial risks. Governments use probabilistic methods for environmental regulation and financial oversight. Even in global markets, traders use probability to guess how events, like a conflict in the Middle East, might change the price of oil. These calculations help signal opinions to other traders and influence the entire economy.

Ultimately, probability serves as a bridge between randomness and order. It provides the tools necessary for statistics, computer science, artificial intelligence, and even philosophy. By using formal terms and mathematical rules, researchers can translate abstract uncertainty into actionable data. Whether through the Kolmogorov formulation of probability spaces or the Cox formulation of propositions, the goal remains the same. We seek to understand the underlying mechanics and regularities that govern the unpredictable world around us.

653 words

Where will your curiosity go next?

Keep exploring at your chosen reading level.

🖼️ Images & Media (6)
File:Dice Distribution (bar).svg
Dice Distribution (bar).svg
File:Cardano.jpg
Cardano.jpg
File:Christiaan Huygens-painting.jpeg
Christiaan Huygens-painting.jpeg
File:Bendixen - Carl Friedrich Gauß, 1828.jpg
Bendixen - Carl Friedrich Gauß, 1828.jpg
File:probability vs odds.svg
probability vs odds.svg
File:Mutually Exclusive and Non-exclusive Probability Events.jpg
Mutually Exclusive and Non-exclusive...
More to explore

What is Nepedia?

A free, ad-free encyclopedia for children. Every article is written at five reading levels, so the same page works for a five-year-old and a fifteen-year-old — use the level switcher above to see this one change. No account needed to read.