Sampling

AQA A-Level Research Methods

Target population

the people whose behaviour we are interested in.

Sample

the people who are tested in the study. (participants)

Representative sample

when the sample represents the target population.

Biased sample

when the sample does not reflect the target population.

Generalisable

the results from the sample can be assumed to apply to the target population.

Sampling Technique

the method used to select the sample

The 5 sampling techniques

• Random

• Stratified

• Volunteer

• Systematic

• Opportunity

Random Sampling

• Everyone in the target population has an equal chance of being selected.

• Every person in target population is numbered, then numbers are pulled out of a hat/ randomly generated to allocate participants.

Stratified Sampling

Target population is broken down into appropriate subgroups and a proportional amount of each subgroup are selected (usually random within subgroups)

Volunteer Sampling

An advertisement is used so people in the target population can put themselves forward by responding to the advert.

Systematic Sampling

A structured way of selecting people from the target population - e.g. selecting every 5th person on a register.

Opportunity Sampling

Using whoever is available at the time and place of the study.