The ASQ-3 cutoff scores are set at 2 standard deviations below the mean. The monitoring zone is between 1 and 2 standard deviations below the mean. Table 18 in the technical appendix (page 171 in the User’s Guide or available here) shows the mean and standard deviations for each ASQ-3 interval. The bell curve is not typical, however, so calculating percentiles is not straightforward.