Risk and probabilty Flashcards
Define ‘probability’
A numerical measure of the chance of an event happening from 0 to 1
In what formats can probability be written?
Fractions, deciamls or percentages
What is meant by conditional probability, and how would it be shown?
The probability that B will happen given that A has happened, shown as P(B|A)
What is the formula for the probability of two mutually exclusive events?
P(A u B) = P(A) + P(B)
What is the general addition law for probability?
P(A u B) = P(A) + P(B) - P(A n B)
What is the formula for probabilit of two independat events?
P(A n B) = P(A) x P(B)
What is meant by two independant events?
One does not affect the other, event A has no affect on event B, and vice versa
Whatis meant by two mutually exclusive events?
Two events that cannot happen at the same time
What is meant by an exhaustive event?
A set of events that contains all possibly outcomes
What is the formula for calculating risk?
risk of event = number of trials in which the event happens / total number of trials
Define ‘absolute risk’
The probability of an event happening
Define ‘relative risk’, and give the formula for it
How many times more likely an event is to happen for one group compared to another group
relative risk for a group = risk for those in the group / risk for those not in the group
What is the general multiplication formula for probability?
P(A n B) = P(A) x P(B|A)
How do you know if two events are independant?
If P(A|B) = P(A) or P(B|A) = P(B)
