Investigation of shifts in autism reporting in the California Department of Developmental Services.

The team checked if California's autism numbers were rising because kids once labeled with mental retardation were simply re-labeled with autism.

They pulled 1996-2007 records from the state Department of Developmental Services.

Workers compared electronic codes against original paper files for the kids.

The codes matched the paper files almost perfectly.

Only a large share of cases showed a clear switch from mental retardation-only to autism.

The rise in autism cases is real, not a paperwork trick.

Richman et al. (2001) showed that autism tests like false-belief tasks are reliable. Wong et al. (2009) now shows the state records are reliable too. Together they mean both the tools and the data are solid.

Kirby et al. (2024) found primary-care doctors diagnose autism a year earlier than specialists. Wong et al. (2009) proves those early labels stick in the state system, so catching kids sooner truly adds them to the count.

Zou et al. (2025) maps China’s new autism policies. Their call for better health-information systems echoes why Wong et al. (2009)’s audit matters everywhere: good data drives good policy.

You can trust California DDS autism counts when you write reports or compare prevalence. The growth is not coding drift, so plan caseloads and staffing for real demand.