Reliability

The extent to which the same result will be achieved when repeating the same measure or study again. There are four types of reliability mentioned on this website:

1. Inter-rater - Persons independently administering the same assessment to the same person should have highly similar results.
2. Internal - Items on an assessment aimed at measuring the same thing or parts of the same thing (e.g., physical symptoms of anxiety) should be correlated.
3. Split-half - A method of measuring internal reliability by verifying that half of the items on a scale are correlated with the other half.
4. Test-retest - A method in which the same measure is administered multiple times and the resulting scores are compared. Assuming no important intervening events, a person's scores on a measure taken multiple times should be correlated.