The confidence intervals in the original paper [1] are surprisingly large:
>Results For Danish children born during the study period, 33% (95% CI, 0%-70%) of the increase in reported ASD prevalence could be explained by the change in diagnostic criteria alone; 42% (95% CI, 14%-69%), by the inclusion of outpatient contacts alone; and 60% (95% CI, 33%-87%), by the change in diagnostic criteria and the inclusion of outpatient contacts.
i.e., there's a 5% error probability that the "true" increase is smaller than 33% or larger than 87%. In other words, the "true" mean is somewhere in between 33% and 87%!
Interestingly, this question is still on the table 50 years after psychiatry/psychology realized that diagnostic criteria were a central issue (hence the Diagnostic Statistical Manual). Since all that is left once there is no genetic (in the wide sense) theory is a set of symptoms, there is a large number of ways in which to arrange such symptoms and therefore likely large variations among the categories thus defined. The vulnerability of a theory is being traded off for the certainty of a number or a range.
Nobody is going to be mad at you for giving such a ridiculously large number but you'll get blasted if your theory is wrong.
Yes, diagnosis of disorders that manifest mostly as behavioral differences is hard. But even if we had complete genome information for all human beings on planet Earth, we still might have trouble with individual diagnosis. That's because identical (monozygotic) twins are often discordant for many kinds of diseases and disorders, including autism.
Current title is "Increase in Denmark’s autism diagnoses caused by reporting changes". I think a more accurate description would be "60% of the Increase in Denmark’s autism diagnoses caused by reporting changes".
Pregnant mother obesity and giving birth well over 30 contribute not only to autism but also plethora of other issues. On average 20 year old pregnant woman has one hundred times lower chances of delivery complications than 30 year old. 300 pound 35 year old behemoth on the McDonald's diet is the reason for crazy autism statistics in the West.
>Results For Danish children born during the study period, 33% (95% CI, 0%-70%) of the increase in reported ASD prevalence could be explained by the change in diagnostic criteria alone; 42% (95% CI, 14%-69%), by the inclusion of outpatient contacts alone; and 60% (95% CI, 33%-87%), by the change in diagnostic criteria and the inclusion of outpatient contacts.
i.e., there's a 5% error probability that the "true" increase is smaller than 33% or larger than 87%. In other words, the "true" mean is somewhere in between 33% and 87%!
[1] http://archpedi.jamanetwork.com/article.aspx?articleid=19196...