define the term target population?
the group of people from whom the sample is drawn
describe opportunity sampling
taking the sample from those available at the time
ie first 20 students you see in a caferteria
describe random sampling
a sample in which every member of the population has an equal chance of being chosen
-identifying every member of the target population and then selecting the number of people u need, so every one has an equal chance
eg put names in a hat
Describe self selected sampling
participants becoming part of the study because the have voluntered as a result of an advert in a newspaper
Describe snowball sampling
when you recruit a participant and then they recruit someone
Give the strengths of opportunity sampling
- cheap
- quick and convinient
- doesn’t require extensive research into participants
- degree of consent
Give the strengths of random sampling
- broad range of people
- high population validity
- not biased
- everyone has an equal chance
Give the strengths of self selected sampling
- people are willing to take part
- degree of consent
- less likely to withdraw
Give the strengths of snowball sampling
- avoids offending anyone
- sense of obligation
- locate people who are difficult to access
Give the weaknesses of opportunity sampling
- doesn’t have high population validity
- people may feel ambushes
- may have similar personalities ie biased
- not representative
Give the weaknesses of random sampling
- time consuming
- difficult to obtain as you may not have everyones details
- may be biased if small
Give the weaknesses self selected sampling
- may try and please the experimenter ie demand characteristics
- share similar characteristics
Give the weaknesses of snowball sampling
- share similar characteristics
- sense of obligation
define the term sample
the group of people selected from a population to represent the population in a study
