Properties of a Random Variable - Definition

A random variable is one whose value depends upon chance and in statistic, such a variable is often called stochastic (equal to guess). Situation where, a set of measured values,

obtained "under the same condition" constitutes a sample of the random variable, x, which is being measured. If the measurement were to be repeated an infinite number of times, the resulting infinite number of values,

would constitutes the population of the random variable x. In surveying, from repeated measurement, this sample we have to deduce characteristic of the population. From the population characteristics (or parameter) we can make deductions about the relative reliability of different measurement and about the most likely value of the random variable x.

Reference: Cooper, M. A. R. (1974). Fundamental of Survey Measurement and Analysis. Great Britain.: Granada Publishing Ltd