A quote: "...several epidemiological studies were conducted supporting this concept and generating novel ideas for the underlying mechanisms that were then followed up by use of well-defined animal models and human studies."
There is inadequate evidence of a link between the hygiene hypothesis and autism, which is what the article was about. I agree that there seems some fairly good support for the hygiene hypothesis and immunological problems, like allergies and asthma.
EDIT: replaced "no evidence" with "inadequate evidence", as lutusp noted, the article is claiming a correlation, which is at least weak evidence.
> There is no evidence of a link between the hygiene hypothesis and autism, which is what the article was about.
The article shows a correlation between the hygiene hypothesis and autism. A correlation, by itself, could mean anything or nothing, but it is certainly evidence.
Are you using "evidence" as a synonym for "proof", as in law? I ask because science doesn't work that way.
This correlation may simply evaporate with further work, or reveal some connection not now apparent, but saying there's no evidence for the correlation is simply false.
To understand why this is true, consider rain and puddles. A naive alien, seeing a correlation between rain and puddles, might conclude that the puddles caused the rain, or the reverse, or both rain and puddles are caused by an unevaluated third cause.
Because A might cause B, or B cause A, or A and B be caused by C, and without researching the true cause-effect relationships, the observed correlation means precisely nothing. No. Thing. It is not weak evidence, it is not evidence at all.
And "hearsay and anecdotes" are not any kind of evidence of interest to a scientist. The plural of anecdote is not data.
He is not talking about causation or not. He is talking about using evidence to affect his (subjective) posterior probability of the truth of a statement.
Of course he is. Here's a quote from the post to which I replied:
> There is inadequate evidence of a link between the hygiene hypothesis and autism ... the article is claiming a correlation, which is at least weak evidence.
But the above is false. A correlation is not "weak evidence" for a cause-effect relationship, or a "link", as the poster put it. We need to be perfectly clear that a "link" suggests a cause-effect relationship, but without specifying which way cause and effect run.
A correlation is an observation that can only lead to further work, and it is never, in and of itself, evidence of a cause-effect relationship, absent discovery of a mechanism.
This reminds me of one of my pet peeves about science journalism -- use of the word "link" to describe a correlation. It's tendentious and misleading. There are lots of studies that find "links" between utterly unrelated things, by simple data mining (searching for coincidental correlations devoid of meaning). Such meaningless correlations are often published as though they mean something, and they're nearly always described with the word "link" or another tendentious word.
> There is some evidence that autism may be caused by an immune disease; One publication speculated that the lack of early childhood exposure could be a cause of autism.
The hygiene hypothesis has wider use than just autism - that a bunch of allergy and auto-immune stuff is caused by excessive cleanliness. There is strong evidence that might be true. But the link between autism and excessive cleanliness is, to quote one link that you provided, "speculative".
The abstract of the other study doesn't mention ASD; maybe I'm missing something?
(Just to be clear, because sometimes I'm not: The hygiene hypothesis is strong and important when talking about allergy and maybe auto-immune diseases; I need convincing that there's any link to ASD.)
Yes -- but my remark is about the hygiene hypothesis, not about autism. Read the post to which I replied. The poster said "There is no evidence for the hygiene hypothesis." I replied to that specific remark.
> The hygiene hypothesis has wider use than just autism ...
What? The evidence for the hygiene hypothesis is strong in many areas, but as to autism, it's mere speculation.
> But the link between autism and excessive cleanliness is, to quote one link that you provided, "speculative".
Yes -- and on what basis do you think I have taken any other position?
> The hygiene hypothesis is strong and important when talking about allergy and maybe auto-immune diseases; I need convincing that there's any link to ASD.
So does everyone else. There's no basis for this assumption in present evidence.
The comment you responded to was clearly talking about the hygiene hypothesis and autism. I'm not sure how you read it otherwise.
Since the post you responded to was saying that there is no evidence for the hygiene hypothesis (as a cause for autism) and you then replied to say that there was strong evidence for the hygiene hypothesis it's a reasonable assumption that you're still talking about causes of autism.
On the contrary, there is copious evidence for the hygiene hypothesis:
http://en.wikipedia.org/wiki/Hygiene_hypothesis#Supporting_e...
PubMed: Epidemiological and immunological evidence for the hygiene hypothesis:
http://www.ncbi.nlm.nih.gov/pubmed/17544829
A quote: "...several epidemiological studies were conducted supporting this concept and generating novel ideas for the underlying mechanisms that were then followed up by use of well-defined animal models and human studies."
Your statement is, simply put, absolutely false.