What is the Difference Between Dependent and Independent Events?

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The main difference between dependent and independent events lies in how they are affected by the outcome of other events.

  • Independent events are events whose outcomes are not affected by the occurrence of other events. In other words, the probability of an independent event happening is not influenced by the occurrence of another event. For example, flipping a coin twice and getting two heads is an independent event, as the probability of getting a head on the second flip is still 0.5, regardless of the outcome of the first flip.
  • Dependent events are events that are affected by the outcome of other events. In other words, the probability of a dependent event happening is influenced by the occurrence of another event. For example, drawing a red ball from a bag of 4 red balls and 3 green balls, and then drawing another ball, the probability of drawing a red ball the second time is dependent on whether a red ball was drawn the first time.

In summary, independent events are not influenced by the outcome of other events, while dependent events are influenced by the outcome of other events.

Comparative Table: Dependent vs Independent Events

The difference between dependent and independent events can be summarized as follows:

Dependent Events Independent Events
The occurrence of one event affects the probability of the other event. The occurrence of one event does not affect the probability of the other event.
Previous events have an effect on following events. Previous events have no effect on following events.
Examples include: buying a lottery ticket and finding a penny on the floor, taking a cab home and finding your favorite movie on cable, getting a parking ticket and playing craps at the casino. Examples include: choosing a card and replacing it, then choosing another card (because the odds of choosing the first card are 1/52, and the odds of choosing the second card are 1/52), choosing anything as long as you put the items back.

In summary, events are independent if they have no effect on each other, and they are dependent if they do have an effect on each other.