Sampling Flashcards
What is random sampling?
obtain a list of members, all names on list are then assigned a number, samples are selcted randomly by number
Strengths of random sampling
unbiased- confounding/extraneous variables should be equally divided between groups, improving internal validity
Weaknesses of random sampling
time-consuming, may end up with an unrepresentative sample, selected participants may refuse to take part
What is systematic sampling?
when every nth member of the target population is selected
Strengths of systematic sampling
method is objective- researcher has no influence over who is chosen
Weaknesses of systematic sampling
time consuming, ps may refuse to take part
What is stratified sampling?
where the composition of the sample reflects the proportions of people in the population
Strengths of stratified sampling
produces representative sample- accurately reflects the population
Weaknesses of stratified sampling
identified strata doesn’t reflect people’s differences, complete representation isnt possible
What is opportunity sampling?
selecting anyone who is available and willing to take part in the study at the time
Strengths of opportunity sampling
convenient and less costly , no list of members of target population required, no need to divide population into different strata
Weaknesses of opportunity sampling
sample is unrepresentative of target population, findings cant be generalised to target population, researcher bias- complete control of selection of ps
What is volunteer sampling?
participants select themselves to be part of the sample
Strengths of volunteer sampling
easy, requires minimal input from researcher, less time-consuming , ps may be more engaged
Weaknesses of volunteer sampling
volunteer bias- may attract a certain profile of person (may all display similar characteristics, e.g more helpful/cooperative): not values which are necessarily representative of the entire population.)
