Cronbach’s alpha

Internal consistency

α ≥ 0.9

Excellent (High-stakes testing)

0.7 ≤ α ≤ 0.9

Good (Low-Stakes testing)

0.6 ≤ α ≤ 0.7

Acceptable

0.5 ≤ α ≤ 0.6

Poor

α < 0.5

Unacceptable