Sampling, Credibility, Generalizability and Bias - Quantitative Research Methods Flashcards
define participants
people who take part in a psychological study
define target population
specific group of people whom they are interested in for their study
define sample
a group of participants that are chosen from the target population to take part in the study
define sampling
the process of finding and recruiting individuals for a study
What is the most important property of sampling
representativeness - a sample must represent the target population by containing all essential characteristics
What is random sampling + 1 EXAMPLE
each member of the target population has an equal chance of becoming part of a sample
e.g. drawing names out of a hat, selecting randomly from a list
advantages of random sampling
more likely to contain all characteristics of the target population, with greater representativeness. Therefore, it has high external population validity and it is easier to generalize results to the wider target population
disadvantages of random sampling
it is impossible to carry out truly random sampling and there is always a chance you could miss a group in the target population
What is stratified sampling + 1 EXAMPLE
the sample reflects the characteristics of the target population. The researcher will study the distribution of these characteristics and then recruit participants in a way that keeps the proportions of the sample the same as the population
e.g. looking at grade point average of school students. Therefore you distribute the groups by their different grades.
advantages of stratified sampling
the sample contains all groups in the population with great representativeness. Therefore, it has a high external population validity and it is easier to generalize results to the wider target population
negatives of stratified sampling
requires knowledge on the characteristics of the target population which can be difficult to find - more complicated
What is opportunity sampling + 1 EXAMPLE
participants are selected based on naturally occurring groups that are easily available
e.g. a psychology class, nursing home
advantages of opportunity sampling
financially more efficient and useful when generalizations are not a priority
disadvantages of opportunity sampling
lack of representation, therefore it has a low external population validity as it is hard to generalize results to the wider target population
What is self-selected sampling + 1 EXAMPLE
participants volunteer to take part in a study, usually in response to advertisements or the internet
advantages of self-selected sampling
quick and easy way to recruit participants, could also have a large representation if the advertisements are targeted to a large population
negatives of self-selected sampling
lack of representation as participants are usually more motivated than the average participants. Therefore there is low external population validity and it is hard to generalize to the wider population
how to measure the quality of an experiment
looking at the internal and external validity