4.1 - Probability Distributions

Statistical Experiment

any process or study which results in the collection of data, the outcome of which is unknown

Variable

Any characteristic that can be measured or categorized

Random Variable

if a variable can assume different values such that any particular outcome is determined by chance. It is denoted by 'x'

A variable is discrete when...

it has finite or countable number of possible outcomes that can be listed. Examples include phone calls made on a given day, the number of employees who use elevators, etc.

A variable is continuous when...

it has uncountable number of possible outcomes, represented by an interval on a number line. Examples include weight, time spent on phone calls in a given day, height, speed of car, age of person, etc

Discrete Probability Distributions

applies the theory of probability to describe the behavior of the random variable. It is an assignment of probabilities to the specific values (discrete case) of the random variable or to a range of values (continuous case) of the random variable

Every random variable has a corresponding...

probability distribution

Expected value

of a discrete random variable is equal to the mean of a random value