Sampling Flashcards
What is a population?
Large group of people that a researcher is interested in studying
What is a sample?
The participants taking part in the experiment, drawn from a target population which it is presumed to be representative of.
What should a sample be?
Generalisable
What do we mean by generalisable sample?
Sample should be drawn to representative of the population
What are the 5 types of sampling techniques?
- Opportunity sample
- Volunteer sample
- Random sample
- Systematic sample
- Stratified sample
What is opportunity sample?
-People who are most available
How to carry out an opportunity sample?
Ask people nearby
Strengths of opportunity sample:
Convenient and quick
Limitations of opportunity sample:
Biased = unrepresentative of target population
What is volunteer sample?
Participants select themselves
How to carry out a volunteer sample?
Advertisement to get the participants to volunteer
Strengths of volunteer sample:
- Willing participants = more likely to engage
- Easy
Limitations of volunteer sample:
Biased sample = participants share similar traits (e.g keen, curious)
Cannot generalise to population
What is a random sample?
Everyone in the target population has an equal chance of being chosen
How to carry out a random sample?
- Lottery method
- Individuals of target population given number, randomly select i.e by random number generator
Strengths of a random sample:
Unbiased = researcher has no influence over who is selected
Limitations of a random sample:
- Representation of population is not guaranteed
- Time consuming a difficult
- Selected participants may refuse to take part/
What is a systematic sample?
Participants selected using a set pattern (sampling frame) - every nth person of the target population is selected
How to carry out a systematic sample?
Every nth person is selected from a list of the target population
Strengths of systematic sample:
Unbiased = objective
Limitations of systematic sample:
Time and effort to make a complete list of population
What is stratified sample?
Participants selected by their frequency in the target population
How to carry out a stratified sample?
Strata are identified, relative percentage of strata represented in sample
Strengths of stratified sample:
-Representative
Weakness of stratified sample:
Stratification not perfect = complete representation is not possible as identified strata can’t reflect all the ways people are different.
