Research Methods: Selecting and Using Participants Flashcards
What is the target group
The part of the population that you’re interested in studying
What is the sample and why do you take one
You can’t include everyone in the target group, so you choose a sample of ppts
The sample should be representative (should reflect the variety of characteristics that are found in the target group) so that the results can be generalised to the whole target group
What is a sample that is unrepresentative
It is biased and can’t be reliably generalised to the whole target group
What is random sampling
When everyone in the target group has an equal chance of being selected
Can be done using names in a hat or a computer could randomly pick numbers assigned to ppts
Advantages of random sampling
Fair
Everyone has an equal chance of being selected
Likely to be representative
Disadvantages of random sampling
Doesn’t guarantee a representative sample - still a chance some subgroups may not be selected
If the target group is large then it may not be practical or possible give everyone a number
What is opportunity sampling
When the researcher samples whoever is available and willing to be studied
Advantages of opportunity sampling
Quick and practical way of getting a sample
Disadvantages of opportunity sampling
Unlikely to be representative of the target group or population as a whole
So findings can’t be confidently generalised
What is volunteer sampling
When people actively volunteer to be in a study by responding to a request for ppts advertised by the researcher e.g. in a newspaper
Researcher may then select only those who are suitable for the study
Advantages of volunteer sampling
If an advert is placed prominently (e.g. a national newspaper) a large number of people may respond, giving more ppts to study
This may allow more in-depth analysis and more accurate statistical results
Disadvantages of volunteer sampling
A large amount of people may respond to the study, but these only include people who saw the advertisement, other people would not have a chance of being selected
People who volunteer may be more cooperative than others, so the sample is unlikely to be representative of the target population
What is systematic sampling
Where every nth name from a sampling frame (record of all names in a population) is taken
E.g. every 3rd name from a register
Advantages of systematic sampling
Simple and effective way of generating a sample with a random element
Means that the population is more likely to be evenly sampled than by using opportunity or volunteer samples
Disadvantages of systematic sampling
Subgroups might be missed
Will not be representative if the pattern used for the samples coincides with a pattern in the population
What is stratified sampling
Where all the important subgroups in the population (e.g. different age or ethnic groups) are identified and a proportionate number of each is randomly obtained
How to carry out a stratified sample
Class of 20 students:
Ten are 16 years old
Eight are 17 years old
Two are 18 years old
A stratified sample of 10 students, the numbers of the different ages must equal 50% of the class, you will need:
Five 16 year olds
Four 17 year olds
One 18 year olds
Advantages of stratified sampling
Can produce a fairly representative sample
Can also be used with random and systematic sampling
Disadvantages of stratified sampling
Can take a lot of time and money to do it
Some subgroups may be missed
Can be difficult to identify traits and characteristics (such as people’s ages or backgrounds) effectively enough to stratify the sample properly
What is the Hawthorne effect
If people are interested in something and in the attention they are getting (e.g. from researchers), then they show a more positive response, try harder in tasks, and so on
This means results are artificially high which could make conclusions invalid
Opposite effect may occur if the ppts are uninterested in the task
(Please you or screw you effect)
What are demand characteristics
There are aspects of a study, which allow the ppts to form an idea about its purpose
If they think they know kind of response the researcher is expecting from them, they may show the response to ‘please’ the researcher (or more deliberately do the opposite)
This would make the conclusions invalid
What is social desirability bias
People usually try to show themselves in the best possible light
In a survey, they may not be completely truthful, but the give answers that are more socially acceptable instead
This would make the results less valid
What is researcher/ experimenter bias
The researchers’ expectations can influence how they design their study and how they behave towards the ppts
Their expectations can influence how they take measurements and analyse their data, resulting in errors that can lead, e.g. to accepting a hypothesis that was actually false
Their expectations may also lead them to only ask questions about what they are interested in, and they may focus on the aspects of the ppts answer which fit their expectations
Investigator effects
These can be anything that the researcher does which can affect how the ppt behaves
If a researcher’s expectations influence how they behave towards their ppts, the ppts might respond to demand characteristics
Also, a researcher’s expectations could result in them asking leading questions
Finally, the ppt may react to the behaviour or appearance of an investigator and answer differently
