P&SIA L1 C3 S5

Intro Stats: Islamic Approach -- Part 2: Probability and Statistics -

Lecture 1: Random Samples, Concept 3: Random Draws

S4: Uniform Random Variable

A uniform random variable assigns equal chance to all outcomes, just like a simple random draw assigns equal probability to all members of the population. Suppose a population P has N members, with serial numbers 1,2,3,...,N . Let W be a randomly chosen element of the population P. Let X(W) be the serial number of W. Then X(W) takes values 1,2,3,...,N and each value has equal probability 1/N. X is called a DISCRETE UNIFORM RANDOM VARIABLE.

The EXCEL function RANDBETWEEN is a real world implementation of a Discrete Uniform Random Variable. If we write =RANDBETWEEN(1,N) in any cell, EXCEL will produce a random number between 1 and N such all integers have equal probability 1/N. This function is VOLATILE -- that means that every time some change is made in the worksheet, EXCEL produce a NEW random number.