sampling methods

Question 1

simple random sample

Answer 1

> put population in unbiased order
number objects 1-n
randomly generate numbers to chose for the sample size
ignore repeats and choose again

AD:
unbiased, cheap, quick
DIS:
mayb not representative, need a list of pop

Question 2

systematic sample

Answer 2

> put population in unbiased order
number objects 1-n
divide population by sample size (sampling interval)
random number between 1 and sampling interval as starting
then add sampling interval to choose next
until required sampling size

AD:
unbiased, quick,
DIS:
need a list of pop, mayb not represent

Question 3

stratified sample

Answer 3

> divide the population into strata
EITHER: amount proportional to size of sample for each strata or equally choose
simple random sample for this number in each strata to get sample
whether proportional –> whether representative

AD:
unbiased, cheap
DIS:
time consuming, also need a list of each strata for random sample

Question 4

quota sample

Answer 4

> divide the population into quota
amount proportional to size of sample for each quota
choose this amount from each sample

AD:
quick, easy
DIS:
mayb not representative, biased

Question 5

opportunity sample

Answer 5

> select available objects from target group
whoever is willing to participate in study.