Probability Introduction
Probability is an incredibly important part of statistics! We can use probability to help us make decisions under uncertainty and make predictions.
Probability (or chance) is the percentage of times one expects a certain outcome when the process is repeated over and over again under the same conditions.
The chance of an outcome is equal to: the # of that outcome / total # of possibilities
Probability Notation
Oftentimes, data scientists use probability notation to express different probabilities:
- Example: P(A) is read as “the probability of event A”
We can calculate simple probabilities with games of chance. For example...
The probability of rolling a fair 6 sided die and getting a 1, is 1/6 because there is only 1 side marked "1" among 6 total sides.
The probability of drawing the queen of hearts from a standard deck of 52 cards is 1/52 because there is only one queen of hearts among 52 total cards.
Probabilities can be expressed as fractions (shown above), decimals, or percentages.