Sampling Techniques

Question 1

Random Sample

Answer 1

A small group is selected from the sampling frame where everybody has an equal chance of being chosen.
Positive- Unbiased/ fair
Negative- May not be representative

Question 2

Systemic Sample

Answer 2

Every nth member (for example every 3rd) of the target population is selected.
Positive- Unbiased
Negative- Still may not be representative

Question 3

Stratified Sample

Answer 3

The sample has the same proportions as the target population, e.g. if the population is 60% female and 40% male, your sample will be too.
Positive- Most representative
Negative- Time consuming, not particularly easy

Question 4

Opportunity/ volunteer sample

Answer 4

Opportunity- This technique involves using anyone who happens to be available at the time and is willing to be involved.
Volunteer- Participants volunteer/ self select, for example in response to an advert.
Negative: Highly unlikely to be representative

Question 5

Snowball Sample

Answer 5

Key individuals are contacted and are asked to suggest others that may want to be involved in the research, e.g. investigating criminals.
Positive: access a larger sample
Negative: Biased sample, people may be similar as they are friends

Question 6

Quota Sample

Answer 6

As in a stratified sample, the sample has the same proportions as the population, e.g. if the population is 60% female and 40% male, your sample will be too. A researcher will then have to meet their quota, e.g. find 100 working class and middle class students.
Positive: Representative.
Negative: Time consuming.