Sampling methods Flashcards
opportunity sampling
- Includes anyone who is available and willing to participate at that time.
- For example, selecting the first person to walk past a doorway.
advantage of opportunity sampling
- easy and available for anyone to do
- does not include a lengthy process to locate the participants therefore it is time efficient.
disadvantage of opportunity sampling
- Much more susceptible to bias which means that it is an unrepresentative sample and is harder to generalise.
- excludes a larger portion of the target population.
Random sampling
- gives everyone the same chance of being selected
- computer programme or pick names out of a hat
advantage of random sampling
- unbiased because everyone has the same chance of being selected and can therefore be generalised for the whole population.
disadvantage of random sampling
- relies on the participants availability, if they have to use someone else instead then it wouldn’t be random.
- could be biased (all girls, all same age).
systematic sampling
- chooses participants from the target population in a systematic way.
- putting names in alphabetic order and choosing the nth name.
- or/ divide the total number of the population with the sample size to obtain the sampling fraction.
advantage of systematic sampling
- the sample will be representative of the total population because the system is objective and can therefor be generalised.
disadvantage of systematic sampling
-time consuming.
- has to be selected randomly in order for the results to be reliable.
self-selected/volunteer sampling
- participants select themselves.
- advertisements in posters, newspapers and magazines
advantage of volunteer/ self-selected sampling
- easy and convenient for the researcher as they only have to advertise it and nothing else
- generally less biased than opportunity sampling as it gives everyone the opportunity to respond
- allows the researcher to target very specific samples in relation to a population
Disadvantage of self-selected/volunteer sampling
- chance that volunteer isn’t a typical member of the target population
- placing of advertisement may influence type of participants being used
- may be time consuming having to wait for enough participants to sign up
Snowball sampling
- used when it is difficult to locate members of a target group (small target group, hidden identities)
- researcher identifies a participant and the ask them to refer or nominate other potential participants
Advantages to snowball sampling
- allows researchers to study issues or topics which may be unavailable through other methods
disadvantages to snowball sampling
- More likely to be biased as it relies on peoples connection, may not get a representative sample of the target group
Stratified sampling
- Identifying the different groups of people in the target group and randomly selecting participants from each group based on the frequency of occurrence in the general population
advantages to stratified sampling
- highly representative sample because the frequency of certain types of people is equal to their frequency in our target population
disadvantage to stratified sampling
- very time consuming as it involves a lot of working out
Quota sampling
Advantages of quota sampling
- sample still has a good chance of being representative of the general population because the rate of occurrence is still the same
disadvantage of quota sampling
- sample could be biased as they are only using sections of the target population
time sampling
making observations for short intervals within a period of time- more detailed
event sampling
all behaviours recorded each time they occur- less detailed
