HW4 CH9,10 - Probability, Independant Events & Bayes' Formula Flashcards
what is probability?
The chance an event will occur
what is sample space?
includes all possible outcomes in an experiment
what is event?
a subset (set) of outcomes of interest of the sample space
what are the probability rules?
- Prob.. is a value that is always between 0 and 1 inclusive (0% to 100%)
- Prob. of an impossible event is 0
- prob. of an event that must occur is 1
what is the complement of event A?
includes all outcomes in the sample space that do NOT belong to event A
what is the complementation rule?
P(Ac) = 1 - P(A)
what is the positive predictive value
the probability that a person has a disease, given that they had a positive test result for the disease
what is log run probability?
when the % of an outcome starts to stabilize down the x-axis the more you do that event
what does the phrase “at least mean”?
x or more
what does the phrase “at most” mean?
x or less
what is the symbol for union?
U
what is the symbol for intersection?
n
what do you do when you see the word “or”
you add
what is the general addition rule?
P(A U B) = P(A) + P(B) - (PA&B)
where outcomes that are in A or B or both
what is the intersection of events?
what is a dependent event?
when one even changes the probability of a 2nd event
what is an independent event?
when 1 event DOES NOT change the probability of a 2nd event
what is conditional probability?
the probability of an event occurring given that another event has already occurred
when events are independent of each other then we can use what rule?
The multiplication rule
what is the sensitivity of a diagnostic test?
the probability that test gives positive result when the person tested does have the disease
Two or more events are disjoint if they have ____ outcomes in common
zero
Chance behavior is ____ in the short run
unpredictable
A density curve can be obtained by smoothing a ____ of data
histogram
P(A or B) = P(A) + P(B) means these events are….
disjoint
The ratio of the probability that an outcome occurs, over the probability that the outcome does not occur, gives the __________ of the outcome
odds
An event is random if individual __________ are uncertain but happen in a predictable manner through time
outcomes
A __________ model is a mathematical description of a random process.
probability
Random Variable?
A variable that has a single numerical value, determine by chance, for each outcome of a procedure
probability distribution
a distribution that gives each value of the random variable and the probability for that value. It can be expressed as a table, formula, or a graph
discrete random variable
random variable whose possible values can be listed
continuous random variable
random variable whose possible values cannot be listed
The Poisson distribution describes the __________ of occurrences of an event in finite intervals of time and space.
count
For the Poisson distribution the probability of an __________ over all possible intervals of the same size is the same.
occurrence
