Random Variable

A random variable is a number whose value is produced by a random process, like the result of a die roll or tomorrow's number of website signups. It is the bridge that turns messy real-world chance into numbers you can add, average, and analyze.

Random variables come in two flavors: discrete ones take separate countable values (0, 1, 2 signups), and continuous ones can take any value in a range (a person's exact height). Choosing which kind you are dealing with decides which distribution and which tools apply.