What is an acceptable level of reliability for a psychometric test?
Posted by Cynthia W on 20 October 2006 04:20 PM

Most psychological societies (e.g., British Psychological Society) and academics (e.g., Devellis, 1991) suggest that an acceptable level of reliability for psychometric tests is:

Ability/Aptitude Tests: .80
Personality Tests: .70

Acceptable and unacceptable levels of the Cronbach’s Alpha coefficient

Alpha coefficient

implied reliability

below .60


between .60 and .65


between .65 and .70

minimally acceptable

between .70 and .80


between .80 and .90

very good

much above .90

consider shortening the scale

(DeVellis, 1991, p.85)

DeVellis, R.F. (1991). Scale development. Newbury Park, NJ: Sage Publications.