sampling Flashcards
What is a population in research?
A group of people who are the focus of the researcher’s interest, where a smaller sample is drawn from the target population.
What is a sample in research?
A group of people drawn from the target population that is assumed to be representative.
Name one sampling technique.
Random samples, systematic samples, stratified samples, opportunity samples, volunteer samples.
What defines a random sample?
All members of the target population have the same equal chance of being chosen - selected using the lottery method.
How is a random sample typically selected?
By creating a list of all members, assigning numbers, and selecting using a lottery method.
What is one strength of a random sample?
Free from researcher bias - researcher doesn’t select participants that may help support their study - high internal validity.
What is a systematic sample?
A sample where every nth member of the target population is selected - for example, every 2nd person in a list is selected as a participant.
Describe the process of creating a systematic sample.
Sampling frame is created and participants are organised, for example, alphabetical order - may start from random point to reduce bias. Researcher works through sampling frame until desired sample is reached.
What is a strength of a systematic sample?
It is an objective method increasing internal validity, as researcher has no control over participants, meaning internal validity.
What is a stratified sample?
A sample reflective of the proportions of certain subgroups in the target population. For example:
40% white, 20% black, 40% asian = 4/10 white, 2/10 black, 4/10 asian in a group of 10 participants.
What is a key weakness of a stratified sample?
It may not be fully representative of the whole target population and cannot reflect the way that everyone is different.
What characterizes an opportunity sample?
Participants are selected based on availability and willingness to participate. Researcher takes the chance of whoever is around at the time of the study, like people in the street.
What is a strength of an opportunity sample?
Saves money and time, convenient, as no names need to be put into a hat.
What is a weakness of a random sample?
Only women could be picked if the sample is small - still a chance the sample isn’t representative.
Time consuming and difficult to complete as all participants must be written down in a list.
Some selected participants may refuse to take part and eventually could turn into a volunteer sample.
What is a limitation of a systematic sample?
Time consuming and not everyone chosen may want to take part.
Still may not be representative of target population, for example, only women may be chosen.
What is a strength of stratified sampling?
Representative sample of population, meaning generalisable and high external validity.
No researcher bias as sample is down to what the strata is like.
What is a limitation of an opportunity sample?
Unrepresenatative of target population as it comes from an ungeneralisable area.
Researcher has control over the selection of people and my avoid people they don’t like the look of or not benefit their study, meaning researcher bias.
