Stochastic process (stɒˈkæstɪk ˈprɒsɛs) is a fancy term used in probability theory to describe the evolution of a random system over time. The word "stochastic" generally refers to anything that involves random variables, while "process" implies a sequence of events that occur over time. The spelling of the word "stochastic" comes from the Greek word "stochastikos," which means "guessing," "aiming at a target," or "hitting a mark." The word "process" is from the Latin "processus," meaning "progression" or "advancement."
A stochastic process is a mathematical model for describing the evolution of a system over time where the future outcomes are not determined by known rules or deterministic functions, but rather by some degree of randomness or uncertainty. It is a collection of random variables indexed or ordered by time, which represents the evolution of a system or phenomenon.
In simpler terms, a stochastic process is a sequence of random events or variables that occur or change over time, typically in a probabilistic manner. It is characterized by its probabilistic nature rather than having fixed patterns or deterministic behavior.
Stochastic processes are widely used in various domains, including mathematics, physics, finance, and engineering, to model and analyze systems that involve randomness or uncertainty. They provide a powerful framework for understanding and predicting the behavior of dynamic systems in situations where complete knowledge or fixed patterns are not available.
There are different types of stochastic processes, such as discrete-time processes (where time is characterized by discrete intervals) and continuous-time processes (where time is continuous). Examples of stochastic processes include random walks, Markov chains, Brownian motion, Poisson processes, and many more.
The analysis and study of stochastic processes involve concepts and techniques from probability theory and statistics. Through mathematical methods and simulations, stochastic processes enable us to make predictions, estimate probabilities, and understand various phenomena that exhibit random behavior.
The word "stochastic" originates from the Greek word "stochastikos", which means "skillful in aiming" or "art of conjecturing". It is derived from "stokhazesthai", which means "to aim or to guess". The term "stochastic process" was coined in the 1930s to describe mathematical models that involve randomness or probability. "Process" refers to the sequence of random events or changes over time that such models seek to describe.