Census - ANS Observes/measures every member of a population
Sample - ANS Selection of observations taken from a subset of the
population which is used to find out info about the population.
,Sampling Frame - ANS A list of individuals (named or numbered) from
whom the sample is drawn
Random Sampling - ANS Every member of the population has an equal
chance of being selected
Systematic Sampling - ANS Every nth person is chosen.
Stratified Sampling - ANS Population is divided into mutually exclusive
Strat and a random sample is taken from each.
Quota Sampling - ANS Interviewer selects a sample that reflects the
characteristics of the population
Opportunity Sampling - ANS Choosing whoever is available
Continuous Variable - ANS Can take any value in a given range
Discrete Variable - ANS Takes specific values in a given range
Conditions for Binomial - ANS Fixed no. of trials
2 possible outcomes
Outcomes are independent
Fixed probability of success
Probability: Independent if... - ANS P(A∩B) = P(A) X P(B)
P(A|B) = P(A)
Probability: Mutually exclusive if... - ANS P(A∩B) = 0
P(A∪B) = P(A) + P(B)
Conditional Probability - ANS P(A|B) = P(A∩B)/P(B)
Probability Addition Rule - ANS P(A∪B) = P(A) + P(B) - P(A∩B)
,If there are 3 events, and A and B are mutually exclusive... - ANS
P(A∪B∪C) = P(A) + P(B) + P(C) - P(A∩C) - P(B∩C)
What is a DRV - discrete random variable - ANS it is a random variable
that can only take certain values
... - ANS ...
probability mass function - ANS a function that gives the probability that
a discrete random variable is exactly equal to some value
what does a probability distribution do - ANS describes the probability of
any outcome in the sample space
P(A/B) = - ANS (P(A n B))
---------------
P(B)
If they are independent events P(A) * P(B) = - ANS P(A N B)
SUM OF P(X=x) = - ANS 1
formula for probability X=r where X is the number of desired outcomes
binomial distribution formula - ANS nCr P^r * (1-p)^(n-r)
p = probability of success
r = number of times you want success
n= number of trials
standard deviation - ANS a computed measure of how much scores vary
around the mean score
general probability addition rule - ANS P(A∪B)=P(A)+P(B)−P(A∩B)
P(A∩B)=P(A)+P(B)−P(A∪B)
, what is an event - ANS a set of possible outcomes - not necessarily
equally likely
sample space - ANS set of all possible outcomes , all equally likely
A ∪ B - ANS means A or B or both
A ∩ B - ANS means both A and B
The rules for tree diagrams are - ANS Select which branches you need
Multiply along each branch
Add the results of each branch needed.
Make sure that you include enough working to show which branches you
are using (method).
Be careful to allow for selection with and without replacement.
if you are told what has happened for the first choice and need to find
second you read off tree diagram
if you are told what has happened for the second choice use formula
sample space diagram - ANS
mutually exclusive events - ANS Two events that cannot occur at the
same time
what is P(A∩B) if two events are mutually exclusive - ANS P(A∩B) = 0
Sampling units - ANS Individual units of a population
what does a census do - ANS observes and measures every member of a
population
advantages / disadvantages of census - ANS advantages :
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