lecture 16 Flashcards
how probability is used to compute P(A) - theorem of tot prob
P(A ∩ Bk) = P(A|Bk) = 0
for some k
describe bayes theorem
for 2 events A and B with P(A) >0 and P(B) >0
P(B|A)= P(A|B) P(B)/P(A)
describe bayes theorem - expansion
if 0<P(B)<1
THEN
P(B|A)= P(A|B) P(B)/P(A|B) P(B) + P(A|B^C) P(B^C)
USING theorem tot prob
can bayes theorem apply to many numbers
yeeee - sum of them under, like using total prob theorem
when can we add conditional probs - bayes theorem
only when conditioning on same event
when is bayes theorem often used
to make probability statements concerning an event B that has NOT BEEN observed given event A that HAS BEEN observed
what is the Prosecutor’s Fallacy:
P(spots|measles) does NOT EQUAL P(measels|spots)
P(evidence|guilt) DOES NOT equal P(guilt|evidence)
bayes theorem can extend to
Multiple events
2 conditional events
chain rule applied to bayes theorem