chapter 4: probability and events and shit like that Flashcards
what is an event?
a set of one or more sample space outcomes
what is the probability of an event?
sum of probabilities of the possible sample space outcomes
which is the simplest probability rule?
the rule of complements
what is the rule of complements
you check the probability of an event that will not occur
you check A, you look at all the sample space outcomes that do not correspond to A
what is the intersection of 2 events (A and B)
the event that occurs when A and B simultaneously occur
what is the union of two events (A and B)
the event that occurs when both A and B occur
how do you find the probability of the union of two events
you add the probability of each event
you subtract the intersection of the two events
what are mutually exclusive events (A and B)?
two events that do not have anything in mutual
they have to sample space outcomes occurring
they have no intersection
they’re union is = to 100%
what is the conditional probability of A|B (A given B)?
the probability of event A, given that event B has occurred
basically, it is the probability of the intersection of A and B divided by the probability of B
can be the other way around as well if B|A
what is the general multiplication rule for probabilities?
to ways to calculate P(A intersection B)
P(A intersection B) = P(A) * P(B|A) = P(B) * P(A|B)
what are dependent events ?
event A is influenced by wether the event B occurs
what are independent events?
P (A | B) = P(A)
P (B | A) = P(B)
what is the multiplication rule for independent variables
P(A intersection B) = P(A) * P(B)
what is a prior probability?
an initial probability to an event that will occur
what is a posterior probability?
a revision made on the prior probability with new information
we can use Bayes’ theorem
