sampling methods Flashcards
define target population
the group that the researcher is interested in studying, from which a smaller sample is selected
define sample
a subset of the target population which aims to be representative of that population
define sampling method
the system used to produce a sample
define random sample
produced by using a random technique in which every member of the target population has an equal chance of being selected
evaluate random sampling
+ no bias every person in TP has equal chance of being selected=sample is representative of TP
- more time&effort need list of all members of the TP, identify sample then contact people identified then ask if they will take part- many people may not want to participate=sample ends up bias
define opportunity sample
produced by selecting people who are willing and available at the time
evaluate opportunity sample
+ easy to do cus you go to people who are nearby= quicker & cheaper than other methods (practical)
- unrepresentative of population especially if taken from one place= results can only be generalized from the sample it was drawn
define systemic sample
produced by selecting every nth person on a list of the target population
evaluate systemic sample
how to do it: researcher needs complete list of TP then select every nth person until they have complete sample
+ no researcher bias researcher has no say over who is selected= increases the representativeness of sample
- can still be bias e.g might end up with all men or all women sample= representativeness not guaranteed
define stratified sample
produced by selecting participants in proportion to their frequency in the target population
evaluate stratified sampling
how- Identify groups: Divide the population into different groups based on characteristics
Select proportionally: Choose a sample size from each group that matches its proportion in the population.
Randomly select: Pick participants randomly from each group
+ most representative out of all the sampling methods cus subgroups identified researcher makes sure they are represented in proportion to the numbers in the TP
_ lengthy process, decision abt which subgroup to use may be biased= reduces representitativeness of sample
define volunteer sample
participants will come to the researcher
evaluate volunteer sample
how- researcher advertises for volunteers by putting an ad
- not likely to be very representative of TP cus they are self selecting
