Offering vouchers for students diagnosed with special needs to attend private schools leads to fewer diagnoses and could save state and federal dollars, according to a new study by the pro-school-choice Manhattan Institute.

More than 20 percent of D.C. public school students are diagnosed with learning disabilities, compared with about 12 percent in Montgomery County and about 14 percent in Fairfax. Educators have long worried that failing districts label students as disabled when, in reality, they are behind academically for other reasons.