samplying methods

random - every member of the target population has an equal chance of being selected

+ representative

+ least biased )equal chance method)

+ researcher has no influence on who participates

- costly

- difficult if target population is big

- very rarely used

opportunity - selecting those subjects that are available at the time

+ simple - no planning required

+ cheap

+ not time-consuming

- not representative

- only restricted to people who are available

volunteer - individuals chose themselves, e.g. answering an advertisement

+ very little time and effot required from researcher

- likely to get a biased, unrepresentative sample because will only appeal to certain types of people.

systematic - chooses subjects in a systematic way, e.g. every 10th person from a list or register

+ to begin with, all population is involved, this is an improvement of the opportunity and volunteer

- not everyone has an equal chance of taking part so unrepresentative

- time consuming

- still possible to get a biased sample

quote - sample must include same proportions

+ quaranteed a mixture of target population

- complicated/more effort

- time consuming / expensive

sratisfied - dividing the target population into important subcategories and then selected members of these subcategories on the proportion that they occur in the target population

+ quaranteed to get a mixture of target population

- complicated

- time consuming

- more effort

- expensive