**Probability theory** is the branch of mathematics concerned with probability, the analysis of random phenomena. The central objects of probability theory are random variables, stochastic processes, and events: mathematical abstractions of non-deterministic events or measured quantities that may either be single occurrences or evolve over time in an apparently random fashion. If an individual coin toss or the roll of dice is considered to be a random event, then if repeated many times the sequence of random events will exhibit certain patterns, which can be studied and predicted. Two representative mathematical results describing such patterns are the law of large numbers and the central limit theorem.

As a mathematical foundation for statistics, probability theory is essential to many human activities that involve quantitative analysis of large sets of data. Methods of probability theory also apply to descriptions of complex systems given only partial knowledge of their state, as in statistical mechanics. A great discovery of twentieth century physics was the probabilistic nature of physical phenomena at atomic scales, described in quantum mechanics.

Read more about Probability Theory: History, Treatment, Probability Distributions, Convergence of Random Variables, Law of Large Numbers, Central Limit Theorem

### Other articles related to "probability theory":

**Probability Theory**- Central Limit Theorem

... The theorem states that the average of many independent and identically distributed random variables with finite variance tends towards a normal distribution irrespective of the distribution followed by the original random variables ... Formally, let be independent random variables with mean and variance Then the sequence of random variables converges in distribution to a standard normal random variable ...

### Famous quotes containing the words theory and/or probability:

“... the first reason for psychology’s failure to understand what people are and how they act, is that clinicians and psychiatrists, who are generally the theoreticians on these matters, have essentially made up myths without any evidence to support them; the second reason for psychology’s failure is that personality *theory* has looked for inner traits when it should have been looking for social context.”

—Naomi Weisstein (b. 1939)

“The *probability* of learning something unusual from a newspaper is far greater than that of experiencing it; in other words, it is in the realm of the abstract that the more important things happen in these times, and it is the unimportant that happens in real life.”

—Robert Musil (1880–1942)