Lecture 5 Flashcards
Role of Probability
What is probability?
the likelihood that an event will occur out of all the events ran (trials/rounds)
What is the probability equation?
p = # ways an event can occur (a possible outcome) / total # of possible events
What are complementary event’s probability total?
p is a total of 1 (100%)
What are mutually exclusive (disjoint) events?
when events A and B CANNOT be occurring at the same time - P(A or B)
What is the equation/rule used to calculate probability of a disjoint event?
addition rule
P(A or B) = P(A) + P(B) - [P(A and B)]
What are joint events?
when events A and B CAN be occurring at the same time and the combination of the two events need to be occurring at the same time to calculate its probability
If both conditions are not an option to be occurring at the same time, what is the probability?
probability is 0
What is conditional probability?
the probability of event A occurring after the assumption that event B has already occurred - P(A | B)
What time of variable can use conditional probability?
categorical variables
What is the numerator when calculating conditional probability?
A’s condition frequency while also meeting B’s condition
What is the denominator when calculating conditional probability?
B’s condition/event total frequency
What are the 6 types of conditional probability tests ran in the medical field?
- sensitivity (true positive)
- specificity (true negative)
- false positive
- false negative
- positive predictive value (PPV)
- negative predictive value (NPV)
Which piece of data always goes in the columns of a table when answering conditional probability?
the GOLD standard test or outcome (A and A bar)
Which piece of data always goes in the rows of a table when answering conditional probability?
the new type of test or screening test (E and E bar)
What is the sensitivity equation?
(screen + | outcome +) =
screen+ and has outcome +/outcome+ total
