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Research Methods - Mock 9th December

Terms in this set (21)

random sampling
every member of the target population has an equal chance of being selected for the study, for example by making a list and then picking names out of a hat
random sampling: advantages
unbiased as all members of the target population have an equal chance of being selected
random sampling: disadvantages
making a list of all members of the target population, picking them randomly and then contacting them with the risk of them saying no can be costly and time consuming - if ppts cannot take part the sample may not be completely random which can result in bias
opportunity sampling
sample is selected from those who are most readily available at the time of the experiment for example asking the first 20 people to walk past to take part in the experiment
opportunity sampling: advantages
the easiest method for a researcher to use and it is not costly or time consuming
opportunity sampling: disadvantages
the sample is inevitably biased as it is drawn from a small part of the target population - e.g. if the sample is selected from people waking in a shopping centre on a monday morning it would be unlikely to include professionals or people from rural areas
self-selected sampling
sample is produced by advertising or asking for volunteers and the participants volunteer themselves to take part in the experiment
self selected: advantages
gives the researcher access to a variety of participants, for example people who read a specific newspaper or live around a particular place, which can make the sample more representative and less biased
self-selected: disadvantages
the same can contain participant bias because participants that volunteer are more likely to have motivated and helpful personalities with extra time on their hands - not accurate representation of the entire population
systematic sampling
participants are selected using a pre-determined system, for example putting them all in a list and then selecting every nth person e.g. every tenth person from the list to take part in the experiment
systematic: advantages
avoids researcher bias because participants are selected using an objective system
systematic: disadvantages
the sample is not truly unbiased unless you select a number using a random number generator and then start with this participant before selecting every nth person after that
stratified sampling
participants are selected according to their frequency in the population and sub groups or strata are identified - participants are selected randomly from each strata in proportion to their occurrence in the target population
stratified: advantages
likely to be more representative of the target population than other sampling techniques - it is a proportional representation of the different strata
stratified: disadvantages
it is time consuming to identify subgroups and then select participants and contact them - it would also take more time if the participant selected denied to take part as the researcher would have to begin the process again
quota sampling
the same as stratified sampling though selection from the different strata (sub groups) is done using a non-randoming technique such as opportunity sampling
quota: advantages
likely to be more representative of the target population than other methods because it is a proportional representation of the different strata
quota: disadvantages
it is time consuming to identify subgroups and then select participants and contact them
snowball sampling
sample is obtained from current participants recruiting further participants from people that they know such as friends and family
snowball: advantages
the researcher is able to include groups of people that are difficult to reach in their sample for example drug addicts and homeless people - though this should only be used when the desired participants are difficult to access
snowball: disadvantages
the sample is unlikely to be a good cross-section and representation of the population as it is selected from friends of friends
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