sampling

define sampling

a subset of a population that is used to represent the entire group as a whole

define target population

group of people from whom the sample is drawn

how do we sample?

1. find a target population

• this is the group of individuals the researcher is interested in e.g. people from the UK

2. then comes sampling

• samples will always be smaller than the population targeted

• ideally the samples should be representative of the wider population and generalisable

define opportunity sampling

choosing participants based on their availability e.g. approaching someone in the streets,corridors, then asking them to take part in an experiment

define systematic sampling

choosing participants based on a predetermined pattern- choosing every nth name from a list of the target population

define volunteer sampling

the participants select themselves to take part in the research- advertising the experiment and stating where participants turn up if they’re interested

define stratified sampling

choosing participants based on their group’s percentage of a population, selecting a number of participants from a group based upon that groups proportion within the whole population

define random sampling

each member in the target population have an equal chance of being selected

which sampling methods are quick and easy?

opportunity + systematic

give an example of opportuity sampling

approaching someone in the streets,corridors, then asking them to take part in an experiment

what is bad about opportunity?

a biased method as participants are chosen at the researcher’s discretion

describe the pros + cons of stratified sampling

pros: highly representative because participants are being chosen in the same proportion, so the results are likely to be generalisable + reduces sampling bias

cons: time-consuming + difficult to carry out

which method is most likely to be representative?

systematic

describe the pros + cons of opportunity sampling

pro: it’s unbiased + partially representative

con: very time consuming, not always representative because participants who are picked may all have the same characterstics

example of random sampling

e.g. placing all the names in a hat and drawing names from it

which method is least likely to be representative?

opportunity

give two cons on systematic sampling

can be biased + unrepresentative

what’s good about volunteer sampling?

no researcher bias + ethical because there’s informed consent

and what’s bad about volunteer sampling?

volunteer bias because people who volunteer may have different characteristics to those who don’t + low representativeness, participants may not apply to the whole target population

give an example of stratified sampling

there’s 60% boys and 40% girls, so you pick 6 boys and 4 girls!