Sampling Flashcards
What is random sampling?
Every member of target population has an equal chance of being picked for sample by putting names in a hat and pulling them out without looking until sample has been selected
What are the strengths of random sampling?
1) no researcher bias as it is left to random chance
2) every chance that sample could be fairly representative, meaning it would be generalisable of target population
What are the weaknesses of random sampling?
1) could be unrepresentative as only one type of person could be chosen just by chance
2) not always practical for a large population
What is systematic sampling?
Taking every nth member of the target population to form the sample
What are the strengths of systematic sampling?
1) no researcher bias
2) sample could be fairly representative, so results would be generalisable
What is the weakness of systematic sampling?
1) not truly representative unless select starting point randomly
What is stratified sampling?
Small-scale reproduction of target population by dividing population in ‘strata’ important for the study. Using random selection, participants are selected within each category in proportions they exist in target population
What are the strengths of stratified sampling?
1) no researcher bias as random selection is used on relevant categories
2) fairly representative as selection is taking from main strata within target population allowing generalisations to be made
What are the weaknesses of stratified sampling?
1) requires a detailed knowledge of target population which may not be available
2) time-consuming
What is opportunity sampling?
Researcher decides on type of participant needed and approaches anyone who appears suitable until sufficient numbers have been obtained
What is the strength of opportunity sampling?
1) relatively time and cost efficient to collect sample as researcher does not need to identify all members
What are the weaknesses of opportunity sampling?
1) likely to be biased as it excludes certain participants as researcher makes selection themselves, means it is unrepresentative and therefore generalisations can’t be made
What is volunteer sampling?
Researcher advertises for participants and they choose themselves by replying to advert
What are the strengths of volunteer sampling?
1) time and cost effective in comparison to other techniques as participants volunteer themselves
2) can reach a very large number of people
3) less chance of participants deliberately sabotaging study
What are the weaknesses of volunteer sampling?
1) likely to be unrepresentative as volunteers tend to be a certain type of individual making it unrepresentative and therefore no generalisations can be made
2) researcher bias is low but still the case as where advert is placed is chosen by researcher which could lead to some bias
