Probability

Definitions

Probability Experiment
Process which leads to well-defined results call outcomes
Outcome
The result of a single trial of a probability experiment
Sample Space
Set of all possible outcomes of a probability experiment
Event
One or more outcomes of a probability experiment
Classical Probability
Uses the sample space to determine the numerical probability that an event will happen. Also called theoretical probability.
Equally Likely Events
Events which have the same probability of occurring.
Complement of an Event
All the events in the sample space except the given events.
Empirical Probability
Uses a frequency distribution to determine the numerical probability. An empirical probability is a relative frequency.
Subjective Probability
Uses probability values based on an educated guess or estimate. It employs opinions and inexact information.
Mutually Exclusive Events
Two events which cannot happen at the same time.
Disjoint Events
Another name for mutually exclusive events.
Independent Events
Two events are independent if the occurrence of one does not affect the probability of the other occurring.
Dependent Events
Two events are dependent if the first event affects the outcome or occurrence of the second event in a way the probability is changed.
Conditional Probability
The probability of an event occurring given that another event has already occurred.
Bayes' Theorem
A formula which allows one to find the probability that an event occurred as the result of a particular previous event.
Factorial
A positive integer factorial is the product of each natural number up to and including the integer.
Permutation
An arrangement of objects in a specific order.
Combination
A selection of objects without regard to order.
Tree Diagram
A graphical device used to list all possibilities of a sequence of events in a systematic way.