Sampling Flashcards
What is random sampling? What is an example?
Every member of the target population has an equal chance.
Example: Putting names into a hat.
What are the strengths of random sampling?
1) No researcher bias - random chance.
2) Could be representative - will be generalisable to the target population.
What are the weaknesses of random sampling?
1) Could be unrepresentative - an unbiased selection does not mean an unbiased sample e.g woman may only be randomly selected (not representative of the target population.)
2) Not practical e.g if the sample size is too large it will be hard to get everyone’s names to put in a hat.)
What is systematic sampling? What is an example?
Taking every nth person of the target population.
Example - every 10th person on a school register.
What are the strengths of systematic sampling?
1) No researcher bias - selection is made via the ‘system.’
2) There is also a chance that the sample could be representative - will be generalisable to the target population.
What are the weaknesses of systematic sampling?
1) Not truly representative - unless you select a starting point randomly.
What is stratified sampling?
Dividing the population into groups important to the studies (age, gender) then using random selection, participants are selected within each category in the proportions they exist in the target population.
Example - college population is 55% female and 45% male and you need 20 students for a sample, place names of all female participants in one hat and male in the other. Then pick 11 from the fable hat and 9 from the male.
What are the strengths of stratified sampling?
1) No researcher bias - random selection is used on the relevant categories within the target population.
2) Fairly representative - selection is taken from the relevant groups which would allow generalisations to be made.
What are the weaknesses of stratified sampling?
1) Requires detailed knowledge of the target population.
2) Time consuming - have to put into groups and then randomly select.
What is opportunity sampling?
Researcher decides on type of participant needed and approaches anyone who appears suitable and keeps doing this until the number they need.
What are the strengths or opportunity sampling?
1) Time and cost efficient - do not need to identify all the members in the target population.
What are the weaknesses of opportunity sampling?
1) Biased - excludes certain participants (people who are not around at the time) + researcher makes the selection themselves.
2) Not representative - not possible to make generalisations to the target population.
What is volunteer sampling?
The researcher advertises for participants. Participants choose themselves by replying to the advert.
What are the strengths of volunteer sampling?
1) Cost and time effective - participants volunteer themselves.
2) Method can reach a large number of people (advert online) which could increase representativeness.
3) Less chance of participants deliberately sabotaging the study - volunteering themselves.
What are the weaknesses of volunteer sampling?
1) Unrepresentative - participants who volunteer will be a certain type of person (Interested in the topic or need money)
2) Could introduce bias (If you volunteer for a study on anxiety it may be because you suffer from anxiety) - cannot make generalisations. + where the advert is placed (if by researcher)
