Methods of Sampling Flashcards
1
Q
What is opportunity sampling?
A
- where you recruit those people who are most convenient or most available, for example, people walking by you in the street or students at your school
2
Q
What is an advantage of opportunity sampling?
A
- easiest method because you just use the first suitable participants you can find, which means it takes less time to locate your sample than if using one of the techniques.
3
Q
What are the disadvantages of using opportunity sampling?
A
- inevitably biased because the sample is drawn from a small part of the target population, for example if you selected your sample from people walking around the centre of a town on a monday morning then it would be unlikely to include professional people (because they are at work) or people from rural areas
4
Q
What is random sampling?
A
- one method is the Lottery method in which a list is obtained of all the people in the target population. all names are put into a lottery barrel or hat
- then the number of names are picked out at random
5
Q
What is the benefit of random sampling?
A
- random sampling is unbiased, all members of the target population have an equal chance of selection.
6
Q
What is a drawback of random sampling?
A
- need to have a list of all members of the target population and then contact all of those selected which may take some time.
7
Q
What is snowball sampling?
A
- current participants recruit further participants from among people they know.
- thus the sample group appears to grow like a snowball
8
Q
An advantage of snowball sampling?
A
- enables a researcher to locate groups of people who are difficult to access, such as drug addicts.
9
Q
Disadvantage of snowball sampling?
A
- the sample is not likely to be a good cross section from the population because it is friends of friends
10
Q
What is self selected sampling?
A
- self selected sampling is done by advertising in a newspaper or on a noticeboard or on the internet
11
Q
An advantage of self selected sampling?
A
- gives access to a variety of participants (e.g. all the people who have read the newspaper) which may make the sample more representative and less biased.
12
Q
A disadvantage of self selected sampling?
A
- sample is biased in other ways because participants are likely to be more highly motivated to be helpful and/or with extra time on their hands. this results in a volunteer bias.
13
Q
What is stratified and quota sampling?
A
- subgroups (strata) within a target population are identified (e.g boys, girls or age groups)
- participants are obtained from each of the strata in proportion to their occurrence in the target population.
- for a stratified sample selection from the strata is done using a random technique.
- for a quota sample selection is done using a non random technique.
14
Q
What is an advantage of stratified or quote sampling?
A
- likely to be more representative than other methods because there is a proportional representation of subgroups
15
Q
What is a disadvantage of stratified or quota sampling?
A
- very time consuming to identify subgroups and then select participants and contact them.
