Borderline | 70 to 84 | 12 to 16 | Formal operations | Read and write at a grade 2 to 8 level |
Mild | 55 to 69 | 8 to 12 | Concrete operations to formal operations | Read and write simple phrases, ability to follow simple instructions using prepositions |
Moderate | 43 to 54 | 5 to 8 | Preoperational to concrete operations | Minimal sight vocabulary, understands 2-step commands |
Severe | Hard to test | 2 to 5 | Preoperational | Telegraphic speech, understands 1-step commands |
Profound | Hard to test | Infancy to 2 | Sensorimotor | Orients to speech, small vocabulary |