Sampling Methods Flashcards
What is opportunity sampling?
Finding people who are available at the time and fit the criteria
What are the strengths of opportunity sampling?
- Easy
- Quick
What are the weaknesses of opportunity sampling?
- Biased as it is only taken from a small group of available people
- Disproportionate to the population
What is random sampling?
Giving every member of the population an equal chance of selection, with the participants being selected using a sampling technique
What is the strength of random sampling?
It is unbiased as all members have an equal chance of being chosen
What is the weakness of random sampling?
Very time consuming as you need a list of the whole population
What is stratified sampling? What is the formula?
- Classifying the population into categories and choosing the participants proportionally
- Group/population x sample size
What is are the strengths of stratified sampling?
- More representative than other methods
- Objective system
What is a weakness of stratified sampling?
Very time consuming to identify subgroups, then contact the participants
What is the strength of systematic sampling?
Unbiased, as it uses an objective system
What is systematic sampling?
Using a predetermined system to select participants
What is the weakness of systematic sampling?
Not truly unbiased unless you select a starting number with a random method and start from that participant, going up by the nth term
What is volunteer sampling?
Putting out an application form and getting volunteers
What is the strength of volunteer sampling?
Variety of participants apply
What is the weakness of volunteer sampling?
Volunteer bias (certain subgroups are more likely to volunteer than others)
