Sampling Flashcards
what is random sampling?
everyone has an equal chance of being selected.
E.G putting names of students in a hat, and picking them out
what is systematic sampling?
every Nth member of the population is selected.
E.G get a list of all the students and select every 5th student
what is opportunity sampling?
people who are available at the time are selected.
e.g. researcher going to the canteen at break time and selecting students who are available.
what is volunteer sampling?
participants self select – volunteer to take part.
e.g. researcher advertises on posters for willing students.
what is stratified sampling?
the sample will reflect the proportions of people in the population.
e.g. researcher identifies groups (strata) they want to be in the sample.
-work out the proportion they’re in
-select students in that proportion.
strengths of random sampling?
-unlikely that the sample will be biased, as the researcher has no control over who is in the sample.
-end up with the same representative sample.
-high population validity
weaknesses of random sampling?
-can take a long time, esp if target population is large
-could still be biased/unrepresentative
strengths of stratified sampling?
-representative of the population
-avoids researcher bias s randomisation also occurs
weaknesses of stratified sampling?
-time consuming and difficult
-identified smaller groups may still not be representative
strengths of opportunity sampling?
-convenient, quick and easy to do.
-saves money and time
weaknesses of opportunity sampling?
-less representative because the sample was taken from the same section of the population
-researcher bias, choice over who to choose.
strengths of volunteer sampling?
-quick and easy to do as participants come to the researcher
weaknesses of volunteer sampling?
-most likely to all be similar participants as they’re all willing, and more eager to please population. Volunteer bias.
strengths of systematic sampling?
-avoids researcher bias as people are selected by a system and the researcher has no influence
weaknesses of systematic sampling?
-time consuming and some may refuse to take part.
-unrepresentative.
