Sampling Flashcards
Random Sampling
-Every member of the target population has an equal chance of being selected
How may a random sample be collected
-Using a lottery system
-Names out of a hat
-Random number generator
Strengths of random sampling
-Reduces researcher bias as they have no influence over who is selected and every member of the population has an equal chance of selection.
-This means the sample is more representative of the target population, increasing populational validity
-Allows for more generalisability
Limitations of random sampling
-Time consuming
-Difficult to obtain a complete list of the target population
-Some participants may refuse to participate
Systematic sampling
-Selecting every nth person from a list of the target population
(E.G every 5th person in a register)
Strengths of systematic sampling
-Reduces researcher bias as they have no influence over who is selected and every member of the population has an equal chance of selection.
-This means the sample is more representative of the target population, increasing populational validity
-Allows for more generalisability
Limitations of systematic sampling
-Participants could refuse to participate
-Time consuming
-Difficult to obtain a complete list of the target population
(May as well use a random sample)
Stratified sampling
-Dividing the target population into subgroups called strata based on shared characteristics, and selecting them proportionally
Example of strata
-Gender
-ethnicity etc
Strengths of stratified sampling
-Researcher bias is reduced as there is random selection within each strata (however they choose subgroup categories)
-Produces a representative sample as the characteristics of the target population are represented, making findings more generalisable
-Can compare results across different groups providing much detailed results
Limitations of stratified sampling
-Strata cannot reflect all the ways in which people are different
-Time consuming
-Could refuse to participate
Opportunity sampling
Selecting the most readily available participants at a time
How may particpants in an opportunity sample be recruited
-Asking people on the streets
Strengths of opportunity sampling
-Convenient
-Quick
-Cheaper
Limitations of opportunity sampling
-May refuse to participate
-Under-representative of the target population as participants are drawn from a specific area and so findings may not be generalisable
-Potential researcher bias as they choose participants and so the sample s not randomly selected and so the researcher may consciously or unconsciously select those who fit their expectations/ easier to deal with
Volunteer sampling
(Self selected)
-Participants choose to take part/ self select after seeing an advertisement.
Strengths of volunteer sampling
-Easy and quick
-Informed consent as participants choose to get involved
Limitations of volunteer sampling
-Volunteer bias as people who volunteer may have certain characteristic E.G more helpful, confident etc. This means that the sample is likely to be unrepresentative, reducing populational validity
Target population
-A specific group of people who are the focus of the research. The sample is drawn from this population
Sample
-A group of people drawn from a target population who take part in a research investigation
Bias
When certain groups are under or over represented within the research sample.
Generalisability
-The extent to which the results of the investigation can be applied to the population
