Statistics Dictionary

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Discrete Probability Distribution

If a random variable is a discrete variable, its probability distribution is called a discrete probability distribution.

An example will make this clear. Suppose you flip a coin two times. This simple statistical experiment can have four possible outcomes: HH, HT, TH, and TT. Now, let the random variable X represent the number of Heads that result from this experiment. The random variable X can only take on the values 0, 1, or 2, so it is a discrete random variable.

The probability distribution for this statistical experiment appears below.

Number of heads Probability
0 0.25
1 0.50
2 0.25

Because the random variable is discrete, the above table is an example of a discrete probability distribution.

See also:   Tutorial: Discrete and Continuous Random Variables