CLASSICAL PROBABILITY
RELATIVE FREQUENCY
SUBJECTIVE PROBABILITY

Probability helps us to figure out the likelihood of an event or outcome happening. It is measured on a scale from 0 to 1 where 0 is the probability of an event never occurring and 1 means the event always occurs.

CLASSICAL PROBABILITY

All possible outcomes are known, are equally likely and independent of any sensory observation of actual events.

P ( A ) = f / n

The probability ( P ) of an event ( A ) equals the favored number of outcomes ( f ) divided by all possible outcomes ( n ).

Example:
The probability of a fair coin toss turning up heads is equal to 1 / 2 or .5

RELATIVE FREQUENCY

It is the measure of the relative frequency of a certain event occurring based on observations of actual events.

P ( A ) = f observed / n observed

The probability P ( A ) is equal to the favored outcomes observed ( f ) divided by the total number of outcomes ( n ).
The reliability of the results is dependent upon how large the number of observations and how representative they are.

Example:
The probability of 70 year old men dying from a heart attack within the next ten years equals the number of 70 year old men who do die of a heart attack within ten years ( f ) divided by all 70 year old men ( n ).

SUBJECTIVE PROBABILITY

This is when we assign our own personal subjective probabilities. It is a measure of confidence and what odds an individual will accept on a particular event.