Sampling methods Flashcards
What are target populations
the population intended to be studied. Generalised to this population
What are sampling frames
Individuals from target population who can be selected as part of the sample. Should represent the target population
Opportunity sampling
When researchers get hold if the first people conveniently available to them from the sampling frame to do the research
+ of Opportunity sampling
Quick and easy to obtain a sample
- of Opportunity sampling
Not fair since not everyone has equal chance of being selected. Bias is inevitable as sample drawn from a small part of target population
Random sample
Fairest method as all members have equal chance of being selected. E.g. pulling out random names
+ of Random sample
Fair since everyone has equal chance of being selected, so unbiased
- of Random sample
Possible for a number of people who are chosen to refuse to be part of research
Stratified sample
Choosing groups that need to be represented, to give a fair cross-section of the population then using random sampling within the group. E.g. split school into registration classes and randomly sample 5 from each class
+ of Stratified sample
Ensure that it’s possible to get participants that represent all parts of the population so it’s more representative than chance sampling
- of Stratified sample
Many of the participants may decide they don’t want to participate
Quota sample
After choosing groups that need to be represented, the researchers choose the individuals who would be most likely to inhibit characteristics of group
+ of Quota sample
Ensure the sample accurately represents all parts of the population, as subgroups are equally represented
- of Quota sample
The biases of the researcher would affect sample
Self selected sample (volunteer)
Researchers advertise to ask participants to take part
+ of Self selected sample (volunteer)
Everyone willing to take part in research because they know the aim of research in advance
- of Self selected sample (volunteer)
Only 1 particular type of person is willing to volunteer therefore results of experiment wouldn’t be true for entire population. Sample therefore biased
Systematic sample
Obtain sample representative of entire population: not random. E.g. select every 10th individual on the register
+ of Systematic sample
Ensure that it’s possible to get participants to represent all parts of the population. Unbiased, due to objective system used to select participants
- of Systematic sample
Not a random sample, so greater probability that some will be selected rather than others
Snowball sampling
Psychologists find participants then ask these participants to find more people willing to take part in sample
+ of Snowball sampling
Possible to obtain specialist sample where it would be very difficult using other method
- of Snowball sampling
Sample all very similar and may know each other, so don’t fully represent the target population
What are observational sampling techniques
Researcher will record the behaviour/events he observes to ensure there is no observer bias. E.g. sample event and time sampling
Sample event
An observational sampling technique, where psychologist who wants to record a specific behaviour will observe participants. Behaviour recorded each time it occurs to create a total score
+ of Sample event
Every event that is relebant is recorded
- of Sample event
All other events/behaviours ignored
Time sampling
Observational sampling technique where psychologists will record the behaviour/events they see at specific times. E.g. every 10 minutes
+ of Time sampling
Less likely to show researcher bias since all behaviour at specific times is measures
- of Time sampling
Can miss lots of important events as it ignores times where it doesn’t measure
