Scientific processes (Sampling) Flashcards
Population
A group of people who are the focus of the researchers interest, from which a smaller sample is drawn
Sample
A group of people who take part in a research investigation. The sample is drawn from a (target) population and is presumed to be representative of that population
Sampling techniques
Psychologists use sampling techniques to choose people to represent the target population
Random sampling
Every member of the target population has an equal chance of being selected
eg. pulling name out of a hat/ name generator
Strength of random sampling
- Free from researcher bias
Limitation of random sampling
- Difficult and time consuming (individuals may be unwilling to take part)
Systematic sampling
A predetermined system is used to select participants
Eg. every fifth person is chosen
Strength of systematic sampling
- Free from researcher bias (not selecting)
Limitation of systematic sampling
- Not truely unbiased, every fifth person may have the same characteristic eg. right handed
Stratified sampling
Subgroups within a population are identified
Strength of stratified sampling
- Free from researcher bias (subgroups are identified)
Limitation of stratified sampling
Difficult to ensure the subgroups in target population are all identified (time consuming)
Opportunity sampling
Selecting anyone who is available and willing to take part in the study at the time
Strength of opportunity sampling
- Quicker and easier and requires less effort from researcher
Limitation of opportunity sampling
- Researcher has complete control over who they approach
