# Statistical independence

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Events A and B are said to be independent if the probability of A occurring is not affected by the probability of B occurring and vice versa.

### Formula

Two events are said to be independent if the probability of both events occurring is equal to the multiple of the probabilities of each event.

#### Examples

- Rolling a 2 on a fair 6 sided die, and then rolling a 3 on second try. The probability of getting a 2 on the first roll is not affected by the probability of getting a 3 on the second roll, or vice versa.
- The outcome of subsequent coin tosses are independent of previous outcomes. i.e. the probability of getting a head or tail on a fair coin is always the same regardless of the outcome of previous tosses.