Chapter 4 Flashcards
Rare event rule for inferential statistics
if the probability of an event is very small, yet it happens anyways, we will tend to question our previous assumption
concept of probability
an exact fraction or decimal between 0 and 1
rounding rule for probability
round to 3 sig figs, if not an exact number
event
a collection of items from a situation
simple event
specific type of event that can be broken down into multiple items
sample space
everything that can happen when an experiment is conducted
probability notation
probability of A = P(A)
relative frequency approximation of probability
probabilities computed using observations
classical approach to probability
computed when equally likely outcomes happen [e.g. P(odd) on a dice]
subjective probability
estimated by recent events and prior knowledge
law of large numbers
as we continue to perform an experiment over and over again, the probabilities will become exact.
compliment
all items in a sample space that were not used by the original event
unusual number of outcomes
when the outcome is far below or above what is expected
compound event
2 or more simple events combined
formal addition rule
P(A or B) = P(A) + P(B) - P(A and B)
initiative addition rule
method that allows us to find the probability of an “or” event without the formula
disjoint events
2 events that cannot happen at the same time
addition rule for complimentary events
all probabilities in a sample space add together = 1
independent events
the first event doesn’t change the outcome of the second event
dependent events
the first event changes the outcome of the second event
formal multiplication rule
P(A and B) = P(A) x P(B)
intuitive multiplication rule
if events are dependent, we will adjust the probabilities as we multiply
5% guideline for cumbersome calculations
if the sample size is less than 5% of the population, then treat dependent situations as independent situations for the sake of computation
conditional probability
probability found with the knowledge that some other event has already happened
permutation
when the order of the items matter toward the number of different outcomes
combination
order does not matter toward the number of outcomes
fundamental counting rule
if first event can happen m ways, and the second event can happen n ways, then together they can happen (m)(n) ways
