reliability & validity

what is reliability?

the consistency of a research study or measuring test

what are the methods of assessing internal reliability?

• split-half method

• inter-observer validity

what is the split-half method?

splitting a test into 2 halves & administering each half to the same individual - if there is a strong positive correlation of +0.8 or more, there is high internal reliability

what is inter-observer reliability?

the extent to which there is agreement between two or more observers

what is internal reliability?

the consistency of results across items within a test

what is external reliability?

the extent to which a measure varies from one use to another

what are the methods of assessing external reliability?

• test-retest reliability

• inter-interviewer reliability

what is test-retest reliability?

assesses whether whatever is being measured has remained stable over time

what is inter-interviewer reliability?

repeating the same interviewer & interview & comparing OR using two interviewers with the same method

what is validity?

if something measures what it claims to

what are the methods of assessing internal validity?

• face validity

• content validity

• concurrent validity

what is face validity?

whether the items on the measuring instrument look as though they are relevant to what you’re researching

what is content validity?

where you ask an expert in the field to check if the items on the list are relevant

what is concurrent validity?

where you get an established test which has already been peer reviewed & used in research & ask your pps to complete your test then this and correlate the scores

what are the methods of assessing external validity?

• predictive validity

• meta-analysis

what is predictive validity?

the degree to which a test accurately predicts a criterion that will occur in the future

what is internal validity?

whether the effects observed in a study are due to the manipulation of the independent variable and not some other factor

how can internal validity be improved?

• controlling extraneous variables

• using standardised instructions

• counter balancing

• eliminating demand characteristics and investigator effects

what is external validity?

the extent to which the results of a study can be generalised to other settings, other people & over time

how can external validity be improved?

• setting experiments in a more natural setting

• using random sampling to select pps