Sampling Flashcards
Sampling
Selection from the target population.
Self-selected sampling
Participants are people who want to take part in the research- they volunteer themselves. The psychologist will place an advert (this could be a poster, a flyer distribution, a TV advert, mail out, etc)
Opportunity sampling
Finding people who are most convenient to get hold of.
Random sampling
Every member of the target population has an equal chance of taking part. For example, giving every person of the target population a number, which are then randomly selected.
Purposive sampling
Purposive sampling- selecting a sample for a particular purpose; participants have particular characteristics (age, gender etc) based on a sample frame. This is often used in studies where a very specific group is the focus of research e.g. Norwegian single mothers between the ages of 18 and 24.
Snowball sampling
A snowball sample is achieved by asking a participant to suggest someone else who might be willing or appropriate for the study. Snowball samples are particularly useful in hard to obtain populations, such as truants, drug users, etc.
Systemic sampling
A systematic method is chosen for selecting from a target group, e.g. every fourth person in a list could be used in the sample. It differs from random sampling in that it does not give an equal chance of selection to each individual in the target group.
Stratified sampling
The sampler divides or ‘stratifies’ the target group into sections, each showing a key characteristic which should be present in the final sample. Then each of those sections is sampled individually. For example, in a study of college students, a researcher might wish to examine people from different course (e.g., social sciences, physical sciences, math).
Pros and cons of self selected sampling
+Participants will be more willing to cooperate
+Quick and easy
+You can find a larger group to work with
- There could be demand characteristics,- so their behavior may not be fully representative because they are keen to help with the research.
- Results cannot be generalized because you are using a specific group
Pros and cons of opportunity sampling
+Very convenient and cheap method
- There is selection bias
- Sample is not representative
- Cannot measure reliability
Pros and cons of random sampling
+No bias – no control over the selection process
+Representative – it is the best way to ensure that your sample represents the target population
-Participants chosen may not want to be involved
-Takes too much time – you have to gather the names of all members of the target population
-Doesn’t work well with a large population because you would have to gather a large amount of data
Pros and cons of purposive sampling
+cost and time effective
+represents particular characteristics
-Based on a very narrow target population so it cannot be generalized easily
- Small sample size
Pros and cons of snowball sampling
+ Quicker to find samples since it is based on referrals
+ Cost-effective
+ Allows for sampling of hesitant subject
-Not representative or generalizable
-Time consuming
-Not easy to find people willing to participate
-Small sample size
Pros and cons of systemic sampling
+quick and easy
-Doesn’t give an equal chance of selection, so it won’t be fully representative
Pros and cons of stratified sampling
+A stratified sample can provide greater precision than a simple random sample of the same size.
- Isn’t fully representative – no representation for characteristics other than the key characteristics
- It is time consuming and therefore more expensive
