Some interesting details in this latest report in Pediatrics reviewing diagnosis patterns of some 9000-or so school children in the U.S. The conclusion: "ADHD diagnosis is likely to be influenced by a child's social and school environment as well as exogenous child characteristics."
ADHD is most likely to be diagnosed in public school, with an older teacher, and in schools with stricter state-level performance accountability laws. There's also a lot of variation in diagnosis depending your racial background.
The authors also bemoan the "inherent subjectivity of the DSM-IV criateria (which include imtems such as "often has difficulty organizing tasks or activities") allows for a range of people (e.g. parents, teachers, health professionals), organizations (e.g. schools, insurers), and environmental factors (eg, cultural attitudes, public policy) to influence the diagnostic process..."
Who Receives a Diagnosis of ADHD?