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23 Cards in this Set
- Front
- Back
Addition Rule
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If A and B are disjoint events, then the probability of A or B is P(AorB)=P(A) + P(B)
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Complement Rule
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The probability of an event occurring is 1 minus the probability that it doesn't occur:
P(A) = 1-P(A^C) |
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Conditional probability
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P(BIA) is read "the probability of B given A"
P(BIA)=P(A and B)/ P(A) |
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Disjoint (or mutually exclusive) events
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Two events are disjoint if they have no outcomes in common. If A and B are disjoint, then knowing that A occurs tells us that B cannot occur. AKA mutually exclusive
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Empirical probability
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When the probability comes from the long-run relative frequency of the event's occurrence, it is an empirical probability
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Event
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A collection of outcomes. Usually, we identify events so that we can attach probabilities to them. We denote events with bold capital letters.
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General Addition Rule
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For any two events, A and B, the probability of A or B is:
P(A or B) = P(A) + P(B) - P(A and B) |
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General Multiplication Rule
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For any two events, A and B, the probability of A and B is:
P(A and B) = P(A) x P(BIA) |
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Independence (informally)
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Two events are independent if the fact that one event occurs does not change the probability of the other
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Independence (used formally)
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Events A and B are independent when P(BIA) = P(B)
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Joint probabilities
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The probability that two events both occur
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Law of large numbers (LLN)
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States that the long-run relative frequency or repeated, independent events settles down to the true relative frequency as the number of trials increase
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Marginal probability
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In a joint probability table a marginal probability is the probability distribution of either variable separately, usually found in the rightmost column or bottom row of the table
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Multiplication Rule
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If A and B are independent events, then the probability of A and B is:
P(A and B) = P(A)xP(B) |
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Outcome
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The outcome of a trial is the value measured, observed, or reported for an individual instance of that trial
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Personal probability
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When the probability is subjective and represents your personal degree of belief
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Probability
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A number between 0 and 1 that reports the likelihood of the event's occurrence. A probability can be derived from a model (such as equally likely outcomes), from the long-run relative frequency of the event's occurrence, or from subjective degrees of belief. We write P(A) for the probability of the event A.
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Probability Assignment Rule
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The probability of the entire sample space must be 1:
P(S)=1 |
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Random phenomenon
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A phenomenon is random if we know what outcomes could happen, but not which particular values will happen
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Sample space
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The collection of all possible outcome values. The sample space has a probability of 1.
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Theoretical probability
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When the probability comes from a mathematical model (such as, but not limited to, equally likely outcomes)
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Trial
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A single attempt or realization of a random phenomenon
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Tree diagram (or probability tree)
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A display of conditional events or probabilities that is helpful in thinking through conditioning
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