A random variable is a function that assigns a unique numerical value to every possible event having an outcome dependent on chance. The random variable will typically be different for each new event, such as a new toss of a coin.
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A '''random variable''' is a [[function]] that assigns a unique numerical value to every possible event having an outcome dependent on chance. The random variable will typically be different for each new event, such as a new toss of a coin. The term was first coined in 1949, and Merriam-Webster defines it as follows:<ref>Merriam-Webster's Collegiate Dictionary 10th Edition (1994).</ref>
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:a variable that is itself a function of the result of a statistical experiment in which each outcome has a definite probability of occurrence - called also ''variate''
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There are discrete and continuous random variables. An example of a discrete random variable is the number of heads observed in the ten tosses of a coin. This random variable can only have the values 0, 1, 2, ... or 10. An example of a continuous random variable is the mileage on your car until it breaks down. It can have any positive value.
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The terminology "random variable" has been criticized as being neither "random" nor "variable". A random variable really consists of a sampling from a certain probability distribution. It is not purely "random" because it is limited by the predefined probability distribution (e.g., "heads" or "tails" in the case of a coin toss, with a likelihood of each determined by the likelihood of each side appearing); it is not a "variable" because it is a sample value from that distribution.
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== References ==
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<references/>
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There are discrete and continuous random variables. An example of a discrete random variable is the umber of heads observed in the ten tosses of a coin. This random variable can only have the values 0, 1, 2, ... or 10. An example of a continuous random variable is the mileage on your car until it breaks down. It can have any positive value.