Sampling Flashcards
What is population?
The large group of people that a researcher is interested in studying, for example college students from the North West.
What is a sample?
Smaller group of the population.
What is Generalisation?
The sample that is drawn should be representative of the population so generalisations can be made.
What is bias?
Most samples are biased in that certain groups le.g. men, students, professionals etc) may be over- or underrepresented
What is a systematic sample?
Using a set system. Participants are selected using a set ‘pattern’ (sampling frame) e.g. list in alphabetical order.
How?
Every nth person is selected from a list of the target population.
What is a random sample?
Every person in the target population has an equal chance of being selected.
How?
Lottery method. All members of the target population are given a number and placed in a hat or computer/phone randomiser used.
Evaluate random samples.
1.Potentially unbiased.
This means CVs/EVs are controlled.
Enhances internal validity.
- Time-consuming
Complete list of population may be hard to get.
Also some participants may refuse to take part.
What is one strength and weakness of stratified sampling?
- Representative method
The characteristics of the target population are represented.
Generalisability more likely than other methods. - Stratification isn’t perfect
Strata cannot reflect all the ways in which people are different
Complete representation is not possible.
Evaluate one strength and one limitation of Systematic samples.
- Unbiased.
The first item is usually selected at random.
Objective method. - Time and effort.
A complete list of the
population is required.
May as well use random sampling.
What is a stratified sample?
Sample reflects proportions of people in certain subgroups (strata) within a population.
Subgroups (or ‘strata’) are identified, e.g. gender or age groups. The relative percentages of the subgroups in the population are reflected in the sample.
What is an opportunity sample?
People who are simply most available, i.e. the ones who are nearest/easiest to obtain.
How?
Ask people nearby, e.g. ask the students in your class to take part or ask people who walk past you at a shopping centre.
Identify one strength and one limitation of the opportunity sample?
- Quick method
Opportunity sampling is convenient because you just make use of the people who are closest.
This makes it cheaper and one of the most popular sampling methods. - Inevitably biased.
The sample is unrepresentative of the target population as it is drawn from a very specific area, such as one street in one town.
This means that the findings cannot be generalised.
What is a volunteer sample?
Self-selecting.
In a volunteer sample, participants select themselves.
How?
Advertise. For example, place an advert in a newspaper or ask people to put hands up to volunteer.
Identify one strength and weakness of the volunteer sample.
- Participants are willing.
Participants have selected
themselves and know how much time and effort is involved.
Likely to engage more than people stopped in the street. - Volunteer bias.
Participants may share certain traits, e.g. want to be helpful.
Respond to cues and generalisation limited.
