Stochastic variable

A stochastic variable (also called random variable) is a quantity which depends on random events. The name is derived from the Greek word stochos (στόχος), meaning "guess".

Examples of a random event are the upper side (head or tail) of a coin being flipped, the moment of nuclear decay, or the erratic movement of a fly on the wall (see Figure).

Related concepts

• error propagation
• mean value
• standard deviation
• statistics