(abbreviated r.v.) A rule (function) assigning a number to each outcome in the sample space. ("-squared") The ratio of regression sum of squares to residual sum of squares, representing the proportion of variability explained by the model. ² is typical expressed as a percent.
"A function that assigns a numerical value to each outcome of an experiment" (Dolciani, 1988). "The outcomes form the sample space of the Random Variable" (Dolciani, Beckenbach, Donnelly, Jurgensen, & Wooton, 1980).
A function which assigns a numerical value to all possible outcomes of an experiment. The values of random variables differ from one observation to the next in a manner described by their probability distribution.
(Or variate.) A variable characterized by random behavior in assuming its different possible values. Mathematically, it is described by its probability distribution, which specifies the possible values of a random variable together with the probability associated (in an appropriate sense) with each value. A random variable is said to be continuous if its possible values extend over a continuum, discrete if its possible values are separated by finite intervals. See probability theory, statistical independence.
In statistics and mathematics, a random variable is a variable that can take on different, random values. Every random variable must follow some sort of probability distribution, although in experimentation one might not know what that distribution is. As a variable with probabalistically predictable values, it is a function in its own right.