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Psychology unit 4 research methods revision
Opportunity sampling- consists of taking a sample of people who are available at
the time of the study and who fit the criteria you are looking for.
Doesn't show the entire population- not representative and therefore
results can be biased
Quick and easy- large sample can be collected which tends to be more
representative of the target population
Random sampling- when every member of the population has equal chances of being
chosen. This involves identifying everyone in the target population and selecting
participants in a way that gives everyone equal chances of being chosen such as
writing names of participants down on equal size pieces of paper, mixing them up
and then picking the required amount of participants.
Small random samples are always biased as they don't represent the whole
Not every participant in the sample will want to take part so you may not
get a representative sample
Time consuming- hard to get a large sample which are usually the most
Stratified sampling- involves classifying populations into categories and choosing
participants from each category in the same proportion as they are in the target
Most representative sampling method as long as the categories are
Time consuming as categories have to be decided as well as writing all the
participants names down before selecting them at random from each
Volunteer sampling- consists of participants becoming part of a study because
they volunteer to do so in response to an advert. The sample is collected by
placing adverts in newspapers, magazines or posters.
Biased as only people who want to take part do so, as they are keen to
take part so are more likely to be affected by demand characteristics
resulting in them changing their behaviours
Quick and easy so a large sample can be collected so the results are more
likely to represent the target population and therefore be more valid.