Internal consistency

The degree to which items on a scale correlate with one another, suggesting they measure the same construct.

Internal consistency is the degree to which the items on a scale are correlated with one another. High internal consistency suggests the items are measuring the same underlying construct. The most commonly reported measure of internal consistency is Cronbach's alpha.

Internal consistency is one form of reliability — a related but distinct concept — and is necessary for a scale to produce trustworthy total scores. If items on a "depression" scale don't correlate, the total score isn't really measuring one thing.

Reliability — The consistency of an assessment's results across repeated administrations and across items.
Cronbach's alpha (α) — A statistical measure of how internally consistent the items on a scale are; ≥ 0.7 is typically acceptable.

Internal consistency

Related terms