BIOSTAT EXAM 2 QUESTIONS & ANSWERS 2024/2025
the mathematical foundation upon which biostatistics is built - ANSWERSProbability
To understand why we can trust random samples and randomized comparative experiments, we must look at _____________ - ANSWERSchance behavior
__________________...
the mathematical foundation upon which biostatistics is built - ANSWERSProbability
To understand why we can trust random samples and randomized comparative experiments, we must
look at _____________ - ANSWERSchance behavior
__________________ is unpredictable in the short run but has a regular and predictable pattern in the
long run - ANSWERSchance behavior
a phenomenon is called __________ if individual outcomes are uncertain but there is a regular
distribution of outcomes in a large number of repetitions - ANSWERSrandom
____________ is the chance that an uncertain event will occur - ANSWERSprobability
__________________ refers to the _______________ of times an event is expected to occur a very long
series of identical repetitions - ANSWERSprobability, proportion
When considering probability, we deal with random phenomena that produces outcomes, such -
ANSWERS•rolling a die
•answering a multiple-choice test question
•undergoing a pregnancy test
any outcome or set of outcomes of a random phenomenon - ANSWERSan event
Events are denoted by - ANSWERScapital letters
•Examples:
A = The event that a coin toss results in Heads
,B = The event that a randomly chosen student is male
The ______________________ of a random phenomenon is the set of all possible outcomes -
ANSWERSsample space S
When an event has been defined in a way that allows for counting, we can determine its probability by -
ANSWERScounting the number of ways it can occur and dividing by the total number of possible events
The probability that event A will happen - ANSWERSP(A)
Any probability is a number between - ANSWERS0-1
an event with a probability of 0 - ANSWERSnever occurs
an event with a probability of 1 - ANSWERSalways occurs
all possible outcomes together must have a probability of - ANSWERS1
If S is the sample space of a random phenomenon, then P(S) = - ANSWERS1
Since an outcome must occur on every trial, the sum of the probabilities for all possible outcomes must
be exactly - ANSWERS1
it is often beneficial to represent probability problems graphically using - ANSWERSVenn diagrams
The entire sample space is usually represented by a rectangular box, and individual events are
represented by shapes inside the box.
•All possible outcomes are contained in the box
•The area inside the box represents the total probability of the sample space.
•The total area inside the box must
, be 1.
•The area inside shapes within the box represent the probabilities of individual events.
•The area inside shapes within the
box must be between 0 and
The probability than an event does not occur is _____________________ - ANSWERS1 - the probability
that the event does occur
If an event occurs 70% of the time, - ANSWERSit fails to occur 30% of the time
the event that A does not happen - ANSWERSA bar, called "A complement"
For any event A - ANSWERSP(A bar) = 1 - P(A)
The _______ of events two events A and B is the _____ that either A or B (or both) occurs -
ANSWERSunion, event
the union of events A and B is denoted - ANSWERSA U B
Thus, the probability that either of the events, A or B, occurs is P(A or B) = P(A U B)
Two events A and B are ______ or ______________ is they ____________ occur at the same time (dying
by falling off a building and getting shot - only one kills you) - ANSWERSdisjoint, mutually exclusive,
cannot
If, and only if, A and B are disjoint - ANSWERSP(A U B) = P(A) + P(B)
-this is the addition rule for disjoint events
The probability that either A happens or B happens is simply - ANSWERSthe sum of the 2 probabilities
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