Reliability

Question 1

What is internal reliability?

Answer 1

• Is a measure of the extent to which something is consistent within itself.
• For example, all the questions on an IQ test (which is a kind of questionnaire) should be measuring the same thing.
• This may not be relevant to all questionnaires, because sometimes internal consistency is not important, for example a questionnaire about fear experiences might look at many different aspects of being fearful.

Question 2

What is External reliability?

Answer 2

• is a measure of consistency over several over several different occasions.
• for example, if an interviewer conducted an interview, and then conducted the same interview with the same interviewee a week later, the outcome should be the same - otherwise the interview is not reliable.