A random variable is a finite or countable variable within a certain interval. For example, the number of births and deaths in a certain area in a certain year, the effective number and ineffective number of a certain drug in treating a certain patient, etc. Discrete random variables are usually classified according to probability quality function, which are mainly divided into Bernoulli random variables, binomial random variables, geometric random variables and Poisson random variables.
Extended data:
Random variables may take different values under different conditions due to accidental factors, so they are uncertain and random, but the probability that these values fall within a certain range is certain. Such variables are called random variables. Random variables can be discrete or continuous.
The value of a random variable can be discrete (for example, the number of dice is only an integer between 1 and 6, and the number of calls received by a telephone station is only a non-negative integer), or it can fill a numerical range or the whole real axis (for example, the displacement of suspended particles in liquid in a certain direction).
Baidu Encyclopedia-Random Variable