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
what is construct validity
- to what extend do the operationalizations reflect the construct
- if the construct is clearly defined in terms of observational behaviour
- operationalization still reflects the construct
e.g. stress
what are the 2 types of external validity
population validity and ecological validity
what is population validity
the extent to which findings can be generalized from the sample to the target population
what is ecological validity
the extent to which findings can be generalized from the experiment to other settings or situations
what does high population validity mean
the sample is representative of the target population and therefore can be generalized
what does low population validity mean
the sample is not representative of the target population, therefore it is hard to generalize to the wider population
what does low construct validity mean
the variables/concept hasn’t been operationlized very well and therefore it doesn’t clearly measure what it is supposed to. The construct isn’t clearly defined
what does high ecological validity mean
the experimental situation is close to real-life situations e.g. field experiments, therefore it is easier to generalize findings to real-life setting and situations
what does low ecological validity mean
the experimental situation is artificial and highly controlled which does not occur in a participant daily lives e.g. lab experiments, therefore it is hard to generalize findings to real-life setting and situations
what are the characteristics of generalizability
construct validity, external validity - population validity + ecological validity
what is the relationship between internal validity and ecological validity
high internal validity = low external validity because the variables are so controlled that it doesn’t reflect the real world. Harder to generalize findings from artificial settings to the real world.
characteristics of credibility
internal validity
what is internal validity/credibility
to what extend is the DV influenced by the IV, how well were the confounding variables kept constant to allow for a cause-and-effect relationship
what does high internal validity/credibility look like
confounding variables are highly controlled or eliminated, therefore there is no bias that could affect the variables
what is validity
refers to the quality and accuracy of an experiment, does it measure what it claims to measure?
what is reliability
the consistency of a measure, how consistent the results are, can they be confirmed in other findings?
how is bias and internal validity related
bias is a threat to internal validity as it reduces the credibility of an experiment
how is bias and internal validity related
bias is a threat to internal validity as it reduces the credibility of an experiment
what are demand characteristics
“participant expectations” where participants understand the true aims of the experiment and alter their results
what is the expectancy effect
when the participants aims to discern the experiments hypothesis with the goal of helping the researcher, or acting in a certain way to give the right answer
what is the screw you effect
when the participant aims to discern the experiments hypothesis in order to destroy the credibility of the study
what is the social desirability effect
when a participant answers in a way that makes them look good to the researcher to avoid embarrassment or judgement
what is a double blind control
the participants don’t know if they are in a control of experimental group and the researcher doesn’t know the aim of the study either
types of order effects
fatigue effect, practise effect, interference effect
what is the fatigue effect
a type of order effect where a participant decreases in performance in later conditions because they are tired or bored with the activity
what is the practise effect
a type of order effect where a participant improves in performance in later conditions because practise has lead to the development of skill or learning
what is the interference effect
a type of order effect where the first condition may influence the outcome of the second condition
e.g. remembering a word from the list in the first condition when trying to recall a word in the second condition
