Reliability is one of the most important quality aspects of measurement instruments. It can be fatal if measurement instruments are not reliable. But how can you determine the reliability of a psychological test or questionnaire?

To estimate reliability several methods can be used, which have pros and cons:
a) test-retest reliability method
b) parallel-forms method
c) split-half method
d) Internal consistency

Keywords:
reliability – test-retest – parrallel-forms – internal consistency – split-half – test – questionnnaire – measurement – diagnostics – research methods – validity

Author: Eskil Burck (Degreed Psychologist)