The trouble with these kinds of studies (and with empirical evidence in general) is that there are often omitted correlating factors left out of the analysis. Doctors would be sure to control diet and other medications, economists would control socioeconomic status, sociologists would look for cultural factors, etc. However, they're not going to do two or three of these sets at once so the result is a biased study no matter who performs it.
In this case I think a good potential omitted factor is the level of parental discipline. Suppose parents A are Dr. Spock laissez-faire with their kids. This is most likely correlated with:
Not sitting still for the family meal
Watching a lot of television
Getting their way in public places
So Junior gets lots of TV dinners, quick snacks, and time with the power rangers so he wants to do karate instead of read Fox in Socks
Parents B run a tight ship and consequently their vegan, free-range fed wonder-child is happy to sit on the magic carpet and hear about anything so long as it's not The Wealth of Nations again.
Applying the overused correlation != causation mantra is a bit cheap, to be fair we must follow the immediate next step, "If correlation != causation, why?" I think here we have plenty of compelling falsifiable narratives to try before we make green key-lime pie illegal.
Well its a shame you didn't read the article, they conducted a placebo controlled study where they randomly introduced these additives into the children's diets. There really should be no systemic effect from self-selection, apart from in the recruitment process (which they don't discuss).
I remember NPR doing a story on this. Their conclusion was that the headline's a little misleading. It should say SOME food additives may cause ADHD behavior in SOME children.
I guess the affect is small and affects those predisposed.
This is much less surprising than the research on Omega 3 fatty acids and hyperactivity.
Researchers found that supplementing problem kids with fish oil had dramatic effects. Youth offenders showed something like a 40% drop in recidivism vs the control. Low grade-level readers mostly rose to grade level within months.
The implication of this is that lousy food is causing criminality and stupidity. The UK government concluded from this research that it would be very cost effective to provide fish oil supplements to school children.
But here's the scary bit: there aren't enough fish in the world. Once they ran the numbers they found it would be impossible.
Common food additives and colorings can increase hyperactive behavior in a broad range of children, a study being released today found.
It was the first time researchers conclusively and scientifically confirmed a link that had long been suspected by many parents. Numerous support groups for attention deficit hyperactivity disorder have for years recommended removing such ingredients from diets, although experts have continued to debate the evidence.
So, the parents and support groups "knew" the answer before there was scientific evidence supporting their claims.
So, they didn't know, they just have an unscientific agenda.
Now the article acts like their position was validated. It was not. It's scientific status hasn't changed whether science happens to reach the same conclusion or not. They are irrational either way.
In response to the study, the Food Standards Agency advised parents to monitor their children's activity and, if they noted a marked change with food containing additives, to adjust their diets accordingly, eliminating artificial colors and preservatives.
That's stupid too. Parents aren't going to monitor children's behavior scientifically. They aren't going to record it carefully and objectively and compare it to control data previously recorded. This advice will simply lead them to act on whims and fancies.
In this case I think a good potential omitted factor is the level of parental discipline. Suppose parents A are Dr. Spock laissez-faire with their kids. This is most likely correlated with: Not sitting still for the family meal Watching a lot of television Getting their way in public places So Junior gets lots of TV dinners, quick snacks, and time with the power rangers so he wants to do karate instead of read Fox in Socks
Parents B run a tight ship and consequently their vegan, free-range fed wonder-child is happy to sit on the magic carpet and hear about anything so long as it's not The Wealth of Nations again.
Applying the overused correlation != causation mantra is a bit cheap, to be fair we must follow the immediate next step, "If correlation != causation, why?" I think here we have plenty of compelling falsifiable narratives to try before we make green key-lime pie illegal.