sampling Flashcards
define population
group of people from whom the sample is drawn
explain opportunity sampling
ppts happen to be available at the time so are recruited convieniently
give strengths of opportunity sampling
- easy method of recruitment –> time saving and cheaper
give limitations of opportunity sampling
- not representative of whole population hence lacks generalisability
- researcher bias as they pick ppts
explain random sampling
all members of the population have the same equal chances of being selected
- each member in a population is assigned a number then a random number generator is used
give strengths of random sampling
- no researcher bias
give limitations of random sampling
- time consuming, need a list of everyone + contacting time
- volunteer bias as ppts can refuse so can lead to unrepresentative sample
explain systematic sampling
predetermined system is used where every nth member is selected from the sampling frame
give limitations of systematic sampling
- avoids researcher bias
- fairly representative
give strengths of systematic sampling
- not truly unbiased unless you use a random number generator first
explain stratified sampling
composition of the sample reflects the varying proportions of people in the subgroups (strata) within the wider population
1) identify strata
2) calculate required proportion needed for each strata based on target population
3) select sample at random from each stratum
give strengths of stratified sampling
- no researcher bias
- representative data due to proportional strata so can be generalised
give limitations of stratfied sampling
- time consuming
- complete representation of target population is not possible as strata cant reflect all differences of wider population
give strengths of volunteer sampling
self reflection where ppt offers to take part
explain volunteer sampling
- easy and not time consuming
- more likely to coorperate
