At AP, Lindsey Tanner has a very sensible report:
Various reports in recent years have suggested autism rates are rising slightly. Experts think that's mostly because of earlier diagnosis, an expanded definition and more awareness, but say they can't rule out a true increase caused by unknown factors.
How many American children have autism? The U.S. government answers that question at least three different ways and says the latest estimate — 1 in 40 kids — doesn't necessarily mean the numbers are rising.
Here's a rundown on the three surveys:
— The latest estimate is based on responses from about 43,000 parents of kids aged 3 to 17. They were asked if their child had ever been diagnosed with autism spectrum disorder, the formal name that encompasses mild to severe cases. The 2016 survey was internet-based; earlier ones were telephone surveys showing slightly higher rates but the researchers say the results aren't comparable,
The nationally representative survey suggests that about 1.5 million U.S. kids have autism — 2.5 percent or 1 in 40.
— The Centers for Disease Control and Prevent collects nationally representative information from in-person interviews. In 2016, it also asked parents of kids aged 3 to 17 about an ever-diagnosis of autism and came up with a rate slightly higher than in previous years but similar to the 1 in 40 estimate.
— The CDC also uses an 11-state tracking system. It's based on health and school records showing which kids meet criteria for autism, focusing on 8-year-olds because most cases are diagnosed by that age. A report from this network released in April, showed that 1 in 59 kids have autism although much higher rates were found in some places. This estimate is considered the most rigorous, but it's not nationally representative.