@jim p @jim p @jim p
do not know what you're talking about. that isn't a gratuitous insult, it's an inference of a fact drawn by me from the evidence of your statements. but of course, it's only probably true. maybe you really do know what you're talking about, and your responses to me are just some elaborate goof, a la Andy Kaufman.

refute? refute what? you're the one who has made bold assertions, devoid of rhetorical support; given which, perhaps the burden is upon you to justify your certainty. Look at this strange remark:

The line between knowledge and opinion (however well informed) is Certainty

What a thing to say. It is wholly divorced from the reality of scientific inquiry. The line between knowledge and opinion is evidence; and in the scientific endeavor, the line between Doubt and Certainty is wisdom -- with Certainty falling upon the less virtuous side of that demarcation. With respect to science, Certainty is the generally the domain of the Young Earth Creationists, Climate Change Denialists, and Flat Earthers: Their certainty is what fixes their minds immutable in defiance of torrents of contrary evidence. (Scientists do make use of a rather gauzy sort of Certainty: It is functional and pragmatic, merely a mindset that allows them to proceed with their experiments undaunted by the actual doubt that stalks the endeavor from the shadows.)
"no reason based refutation"? I pointed out the obvious, which is that a scientific conclusion is drawn, not from certainty, but from an accumulation of evidence that renders doubt increasingly, but never entirely, untenable; [EDIT: to fix a "sign" error] and renders the conclusion ever more statistically improbable. The remaining improbability is almost invariably expressed explicitly in the scientific paper reporting the results. There's your damned "reason based refutation," right in front of your eyes. If you have any actual argument to offer then feel free to do so, but spare me the empty pseudo-philosophy.

Mind you, we are considering here certainty in the context of science. Consider, alternatively, the "sig" that, at the time of this writing, follows each of my comments: It is a series of three assertions (by me) of facts, facts I have labeled "indisputable". My certainty there is not a matter of scientific inquiry, of repeated experiments, each a collection of measurements subject to all manner of variability that creates around them a cloud of UNcertainty. But even my three certainties are, my labeling notwithstanding, doubted by others. Yes, to entertain such doubts requires a rather astonishing cognitive need for the truth to be other than what it is; nonetheless, there is doubt. Indeed, it's almost incorrect to call them "doubts" -- those who would gainsay my assertions tend to be rather certain that I am wrong. I think they are ... funny. And wrong. Who is to say, which of us suffers from delusional hubris?

Oh, but how weary I am, weary, weary, weary, of being asked to defend arguments I have never made, of being ordered to refute arguments others have never made, of having a straightforward argument rejected by those who decline to read, properly read, what is written, but having cursorily "decoded" the text, as those who study the phenomenon of reading would label its most elementary process, close their eyes, put their fingers in their ears, and refuse to acknowledge that they have been told. Well, sir, I say that you have been told, a claim whose truth value can never be finally adjudicated, but is nonetheless independent of any acknowledgment from you. You're free to presume as you like, but your certain presumption of yourself as qualified to lecture me on the epistemology of science -- or for that matter, any epistemology at all -- is not something you've rooted in careful analysis of the available evidence; it's just something you've claimed for yourself by virtue of "dibs".

#3.1.1.1.1.1 you have no reason-based refutation, still. The line between knowledge and opinion (however well informed) is Certainty. Waving certificates and wearing humble white robes does not erase that line.

@Sima
the original commenter seems to think aren't actually happening, that rising diagnosis rates include factors such as you observe: The emergence of funding for autism therapy and education accommodation has made autism a more "acceptable" diagnosis to parents and practitioners. Also important is just that the diagnosis is less stigmatized than back in the day when the fraud Bettelheim accused "refrigerator mothers" of being responsible for autistic onsets.

Interestingly, though, the 1966 UK study that is the source of the 1/2500 figure probably would have counted your sister. It was based, not on diagnosis rates, but on a comprehensive survey of all the 8-10 year-olds in one UK county. It applied a very stringent screen: Of the 35 children identified as autistic, 30 had IQs below 80 (lowest 30%), but most had IQs much lower than that (lowest 1%).

The 1/50 numbers being bandied about are also estimates of prevalence in the US population, not actual diagnosis rates, and they are for Autism Spectrum Disorder, which includes two broad and diagnoses (Asperger Syndrome and Pervasive Development Disorders) that are much more common than autism itself (even with the more relaxed diagnostic criteria versus 50 years ago). These by themselves account for at least 80 or 90% of actual diagnoses. BTW, 2013's DSM-5 actually tightened the criteria somewhat. Anyway, prior to that, diagnosis rates had probably risen by 40 or 50% over the previous 10 years. Significantly, rates amongst blacks and latinx children increased relative to whites -- though they still lagged well behind. It's not hard to intuit what's going on there, but what it isn't is an actual rise in the occurrence of ASD amongst those populations.

There are known phenomena that may be boosting actual ASD rates, including our success at keeping preemie babies alive -- preemie birth being correlated with higher rates of ASD. And there could be important dietary factors -- there are some wacky results coming from researchers looking at the gut microbiome. My main takeaway would be this:

A. Prevalence rates of ASD in the US may be overstated, possibly by a factor of 2, at least with respect to the diagnostic criteria. Rates almost certainly are at least 1/100 though.
B. Most of the difference between the rates estimated today versus those in the 60s and early 70s are due to changes in the definition itself, which rolled far more common diagnoses than classic autism into the umbrella of ASD.
C. Rises in diagnostic rates of different forms of ASD, including classic autism as well as Asperger's etc., are due primarily to heightened awareness by both parents and practitioners, as well as heightened acceptability of the diagnosis.
D. Nonetheless, ASD likely is increasing somewhat within the US, for several reasons, none of which are well understood.

#3.1.1.1.2.1 I am very late to this but just wanted to say, I wholeheartedly agree with you.
I have personal experience in this. My sister, born in 1965, is severely autistic - non-verbal, non-functioning, needs lifetime care, autistic. She's wonderful, lovely, and autistic. When she was very young in order to get help for her in school, the authorities classified her as retarded. This is because there was no funding for autistic education or help, only for retarded. That classification changed as the funding became available, mostly due to very hard work by people like my parents. Then we got the movies about autistic people, and learned about 'idiot savants' and so on and autism became, I dunno, popular. It's recognized, the spectrum is recognized, and many are diagnosed as on that spectrum.