Flashcards
Types of Sampling
Cards in this deck (14)
- 1Random SamplingEach member of the population has an equal chance of being selected. eg placing names of the target population and draw out the desired number. Or through computer models to generate random lists. This results in a sample selected in an unbiased fashion
- 2Strengths of random samplingUnbiased selection - there is no bias in selection, increasing the chances of getting an unbiased and thus representative sample
Generalisation - sample should be representative, results will be generalisable to the target population - 3Opportunity SamplingInvolves selecting participants who are available and are willing to take part, eg asking people in the street who are passing
Sears (1986) found that 75% of university research studies use undergraduates as participants simply due to convenience - 4Strengths of Opportunity samplingEase of formation - relatively easy to create, as they use people who are readily available
Natural experiments - with natural experiments opportunity sampling usually had to be used, as the researcher has no control over who is being studied - 5Weaknesses of opportunity sampling-Unrepresentative - likely to be biased by excluding certain types of participants and thus be unrepresentative, so that findings cannot be generalised to a target population
-Self-selection - participants have the option to decline to take part and the sampling technique thus turns into a self-selected sample - 6Volunteer (self selected)samplinginvolves people volunteering to participate. They select themselves as participants often replying to adverts
- 7Strengths of volunteering sampling-Ease of formation - Requires effort from the researchers(other than producing an advert) as participants volunteer themselves
-Less chance of 'screw you' phenomenon- as participants are eager to take part there will be less chance of them deliberately trying to sabotage the study - 8weakness of volunteering-unrepresentative- the sample will be biased, as volunteers tend to be a certain type of person and thus unrepresentative, making results not generalisable to a target population
- Demand Characteristics- volunteers eager to please, which increases the chances of demand characteristics - 9Systematic Samplingtaking every nth person from a list to create a sample. Calculating the size of the population and then assessing what size the sample needs to be to work out what the sampling interval is. eg; 1000 divided by 20 = 50 so 50th name on list of employees
- 10strengths of systematic sampling-unbiased selection - There is no bias in selection, increasing the chances of getting an unbiased and thus representative sample
- Generalisation - The results are representative of the population unless certain characteristics of the population are repeated for every nth person, which is unlikely - 11weaknesses of systematic sampling-Periodic traits - the process of selection can interact with hidden periodic trait within the population. If the sampling technique coincides with the frequency of the trait, the sampling technique is neither random nor representative of target pop.
-Not representative - unbiased selection doesn't guarantee unbiased sample. ie all females picked - 12Stratified SamplingIs a small scale reproduction of a population. it involves diving a population into characteristics important for research. eg class, age. then the population is randomly sampled into each stratum (category)
if 12% of the pop. is between 20 and 30 years old the 12% is randomly selected from that age sector - 13strengths of stratified sampling-Representative - as selection occurs from representative sub-groups within a population, the sample should also be fairly representative
- Unbiased - as random sampling is performed upon sub-groups of a population, selection is unbiased - 14weaknesses of stratified sampling-knowledge of population characteristics required - satisfied samples require a detailed knowledge of the population changes, which may not be available
- Time-consuming - the dividing of a population into straturms and then randomly selecting from each can be time consuming
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- AS - Level Psychology (Research Methods) Flashcards on Types of Sampling, created by sienna.a.wells on 24/01/2016.
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