sampling Flashcards
(29 cards)
random sampling
the sample selected at random eg random number generators
random sampling advantages
everyone has equal chance of being selected
quick and easy to carry out
random sampling disadvantages
as the sample being gathered is random - might mean not all social groups equally represented
requires accurate, up-to-date and complete sampling frame
systematic / quasi - random sampling
where you select every nth name from a list
systematic advantages
ensures every individual has an absolutely equal chance of being selected
quick and easy to carry out
systematic disadvantages
could be unrepresentative eg more males than females
requires accurate, up-to-date and complete sampling frame
stratified random sampling
draw sample randomly than stratify sample so it represents the general population
stratified random sampling advantages
ensures control of variables such as age or sex that are important to research
can increase precision and so improve representativeness of your sample as it more closely matches general population
stratified random sampling disadvantages
complex and time-consuming to identify strata and to sample various sub-groups of the population
sampling frame may not contain the required information to split sample-population into groups
values and views on society may influence choice of stratification - bias
cluster sampling
population divided into groups (clusters) and a random sample of these clusters is selected
all observations in the selected clusters are included in the sample
cluster sampling advantages
useful if a complete list of the population is unavailable but you can get a complete list of groups or clusters of the population
cheaper than random sample if the list of subjects is widely scattered
cluster sampling disadvantages
could be unrepresentative as the clusters may not accurately reflect the general population
quota-sampling
researcher tries to find a specific number of a particular person
once that quota is filled they stop
quota-sampling advantages
can control variables without a sampling frame
cheap and quick
quota-sampling disadvantages
not random - each person does not have some chance of being asked
may have to ask personal questions to discover whether respondent matches the necessary criteria of the study
not representative as quota sampling will normally target specific groups in society while non-random nature of the technique means it is unlikely to be truly representative
snowball sampling
respondent recruits one individual who will get more people - snowball
snowball advantages
no sampling frame needed
can allow access to sensitive, marginalised and secretive groups
snowball disadvantages
not representative - people included are part of a network of contracts so are likely to be of similar backgrounds and share values
may run out participants making it difficult to generalise
those who take part are self-selected - those who volunteer may be different from those who refuse
purposive sampling
when you target specific individuals you wish to sample
purposive advantages
hopefully get access to exact people you wish to study
purposive disadvantages
not representative of wider population
small sample sizes
volunteer sample
volunteer to take part in the study, replying to adverts ect
volunteer advantages
no need for a sampling frame
you will normally advertise in areas where people who are appropriate for the study may be
can allow access to sensitive, marginalised and secretive groups
volunteer disadvantages
unlikely to be representative of general population - those who volunteer will normally have a reason for doing so - make them different in some ways to the wider population
may not get a large sample depending on how many people volunteer
