Research methods 9.1.2 - sampling techniques Flashcards
what is random sampling?
when members of the target population are selected without bias so everyone has an equal chance of selection
eg. each person in target population could be given a number, and then the sample could be selected by generating random numbers on a computer and using the member with the corresponding number
what are strengths of random sampling?
allows you to identify sample without bias
what are weaknesses of random sampling?
not really suitable for when target population is large - requires list of everyone in target population
can’t guarantee representative sample - even if you select people randomly, the sample could still end up all-male
slow and inconvenient
what is stratified sampling?
when members of the target population are selected without bias but the sample is guaranteed to be representative in certain ways
strata are sub-groups with the target population eg. girls
the method requires researchers working out which strata are needed in the sample and how many people there should be in each (make it representative of size of that strata in target population)
strata are then filled through random sampling
what are strengths of stratified sampling?
unbiased
more representative than random sampling because all sub-groups are represented
what are weaknesses of stratified
slow and inconvenient
requires list of everyone in target population
may be difficult for researchers to decide which strata are important
some strata are hard to operationalise eg. may want sexual orientation as strata, but this information could be hard to find out
what is volunteer sampling?
members of target population select themselves
eg. volunteers may be recruited through advert on notice board or social media
what are strengths of volunteer sampling?
good for studies with boring/stressful tasks - sample may be more committed than those who are asked
more varied sample than opportunity sampling and there is no researcher bias
what are weaknesses of volunteer sampling?
sample may be unrepresentative because researcher has no control and certain types of people may be more likely to volunteer eg. those that like psychology
advert may be inaccessible to some members of target population if they speak a different language or don’t use social media
slow as researchers have to wait for volunteers to come forward
what is opportunity sampling?
sample is members of target population who are available at that time
eg. researchers may use their friends or approach passers-by on the street
what are strengths of opportunity sampling?
quick and convenient
what are weaknesses of opportunity sampling?
not everyone in target population has equal chance of selection
risk of experimenter bias because only those who are near experimenter or who they know have chance of selection
