* Estimates are based on household interviews of a sample of the civilian, noninstitutionalized U.S. population. One child aged <18 years was randomly selected per family; a parent or other knowledgeable adult provided information for each child. Prevalences of learning disability and attention deficit hyperactivity disorder (ADHD) are based on questions that asked, "Has a representative from a school or a health professional ever told you that (the sample child) had a learning disability?" and "Has a doctor or health professional ever told you that (the sample child) had ...attention deficit hyperactivity disorder (ADHD) or attention deficit disorder (ADD)?," respectively. Unknowns with respect to learning disability and ADHD are excluded from the denominators.
† 95% confidence interval.