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AP Stat03 Anticipating Patterns Cheat Sheet (DRAFT) by

This is a draft cheat sheet. It is a work in progress and is not finished yet.


a measure of the likelihood of an event
any process resulting an observ­ation or outcome
sample space
a set of all possible outcomes of an experiment
tree diagram vs cross table vs venn diagram
probab­ility rules
PA [0,1]
odds in favor of an event: P(A):P(A')
comple­ment: PA = 1-PA'
union: P(A)+P­(B)­+P(AB)
intersect: P(A)P(B|A)­=P(B)P(A|B)
condit­ional event: P(A|B)­=P(­AB)­/P(B)
indepe­ndent: P(AB)=­P(A­)*P(B), P(A)=P­(A|B), P(B)=P­(B|A)
disjoi­n/e­xcl­usive: interrsect is 0
exampl­e:s­hopper items vs gender
autoin­sur­ance: collision protection vs involved in accident

random variables and their prob distri­bution

a quantity whose value varies from subject to subject
probab­ility experi­ement
an experiment with possible outcomes maybe known, but exact outcome is a random event, no certainty could be predict in advance
random variable
outcome of a probab­ility experiment is numeric
discrete random variable
quanti­tative variable that takes a countable number of values
could you have half unit of your variable? No
continuous random variable
quanti­tative variable that can take all the possible values in a given range
could you have half unit of your variable? Yes

discrete random variable distri­bution

Probab­ility distri­bution of discrete random variables
table{ X,p(xi) }
P(xi) [0,1] sum(P(­xi)=1
Mean/e­xpected value
sum((x­i-mean)2*P(xi) )
standard deviation
expected values for how much any given data point will vary from the mean