6/14/2009

Availability heuristic says autism is everywhere

Doug writes:
“grew up out in the country. Everyone knows everyone.I could even tell you who the slow people were. There weren't any special education classes in our schoel. I would know if ANY person in our area was autistic.”
http://www.huffingtonpost.com/harvey-karp/cracking-the-autism-riddl_b_213730.html?show_comment_id=25655328#comment_25655328

To which I respond:

Not the point. You assume this sample represents the population You assume that your personal experience represents the population. Availability heuristic.It would be like me looking out my window and saying I don't see any lions around. Nope, never seen one. Must not exist.

Which garners this response from him:

“But now you can't even walk outside because of all the lions.”


It’s still availability heuristic. Some statistics that counter the idea that autistic children are everywhere in the sense that he means (large proportion of population):

“Results from these two national surveys of parental report of diagnosed autism suggest that, as of 2003--2004, autism had been diagnosed in at least 300,000 U.S. children aged 4--17 years. Parents who reported that their children had autism also reported these children experienced moderate or high levels of social, emotional, and behavioral difficulties and needed special health-care and educational services. These population-based surveys might be useful to assess the specialized health and educational needs of families and children with disabilities such as autism.”
“This report describes the results of that analysis, which indicated that the prevalence of parent-reported diagnosis of autism was 5.7 per 1,000 children in NHIS and 5.5 per 1,000 children in NSCH”
http://www.cdc.gov/mmwr/preview/mmwrhtml/mm5517a3.htm?s_cid=mm5517a3_x


“In 2001, the 89 million children through the age of 21 in the United States represented 31.2 percent of the total population.”

http://mchb.hrsa.gov/chusa03/pages/population.htm

“Developmental disabilities affect approximately 17% of children younger than 18 years of age in the United States and have resulted in substantial financial and social costs for affected families and educational and health care systems.”

http://www.cdc.gov/ncbddd/dd/ddsurv.htm


“McLaren and Bryson (1987) reported that the prevalence of mental retardation was approximately 1.25% based on total population screening. When school age children are the source of prevalence statistics, individual states report rates from 0.3% to 2.5% depending on the criteria used to determine eligibility for special educational services, the labels assigned during the eligibility process (e.g., developmental delay, learning disability, autism, and/or mental retardation), and the environmental and economic conditions within the state (U.S. Department of Education, 1994). It is estimated that approximately 89% of these children have mild mental retardation, 7% have moderate mental retardation, and 4% have severe to profound mental retardation. In addition, McLaren and Bryson (1987) report that the prevalence of mental retardation appears to increase with age up to about the age of 20, with significantly more males than females identified.”


http://www.uab.edu/cogdev/mentreta.htm

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