Sampling Flashcards
What is a sample opposed to a population?
Sampling involves selecting participants from a target population. The target population is the particular subgroup to be studied, and to which the research findings will be generalised.
Why should you use a sample?
A target population is usually too large to study in its entirety, so sampling techniques are used to choose a representative sample.
What are the 5 sampling techniques?
Random, systematic, stratified, opportunity, volunteer
What is random sampling?
All members of the target population have an equal chance of being chosen. Could be achieved by picking names from a hat.
Random sampling evaluation:
STRENGTH- Free from Researcher Bias as the sampler has no control over who is selected. The sample is likely to be representative of the general population.
WEAKNESS- difficult and time consuming task. Individuals who are picked may also be unwilling to take part.
What is systematic sampling?
A system is applied to select participants to make up the sample. Eg: every Nth person
Systematic sampling evaluation:
STRENGTH- Free from researcher bias since the researcher is not selecting participants by choice, but by following a predetermined system
WEAKNESS- every Nth person may have a particular characteristic in common. Although it would be fairly unlikely, it remains a possibility.
What is stratified sampling?
This sample is a proportional representation of the target population. Proportions of the groups within the sample are based on pre-existing factors eg if there is 70% females then the sample size would be 70% females.
Stratified sampling evaluation:
STRENGTH- Largely free from researcher bias. The sample is generated randomly once the subcategories have been identified and therefore be representative of the population.
WEAKNESS- Not a perfect process since the subgroups identified cannot possibly reflect all the individual differences that exist between those in the target population.
What is opportunity sampling?
Anyone who is willing and readily available, being there at that moment in time and being asked.
Opportunity sampling evaluation:
STRENGTH- In comparison to all other sampling methods, obtaining an opportunity sample is quicker and easier since it requires less effort
WEAKNESS- collected from the same place eg uni campus, don’t represent the population. Increased risk of investigator bias.
What is volunteer sampling?
This is ‘self-selected’. Participants select themselves to be a part of the sample, and volunteer themselves.
Volunteer sampling evaluation:
STRENGTH- Quite easy to do and gives you access to a variety of people you normally wouldn’t have access to
WEAKNESS- issue of bias. Those more curious or inquisitive in nature may volunteer, not representative- hard to generalise.
