2.3.2 Non probability sampling Flashcards
what is involved in non probability sampling?
no sampling frame
not everyone in target population had equal chance of being selected
simpler methods
what are the four non probability sampling methods?
opportunity sampling
self selected sampling
snowball sampling
quota sampling
what is opportunity sampling?
select participants from those of the population available at the time
what are strengths of opportunity sampling?
easy to conduct
cheap
simple and convenient
what is a weakness of opportunity sampling?
sample is unlikely to be representative
what is self selected sampling?
participants select themselves e.g. in response to an advert
what is a strength of self selected sampling?
participants volunteer themselves, so they are willing which means you likely will have reduced drop out rates
what is a weakness of self selected sampling?
majority of target population unlikely to respond
unrepresentative
those who respond will be atypical
give an example of how a self selected sample may be atypical:
e.g. research involving maths - people who like maths or who are good at it are likely to respond
what is snowball sampling?
ask initial participant to suggest others who may be appropriate and willing to participate
what is a strength of snowball sampling?
useful for accessing hard to track populations such as gangs or drug users
what is a weakness of snowball sampling?
researcher has little control over sample
unrepresentative - participants nominate people they know well - similar traits and characteristics
what is quota sampling?
the researcher divides the population into sub categories (like stratified) and then meets the proportion of quota using opportunity, self selected or snowball sampling,
what is a strength of quota sampling?
most representative non probability sampling method
what is a weakness of quota sampling?
time consuming
