Comment Re: Correlation is not causation (Score 1) 221
A fair point. So I took your advice and followed the links to the actual article. It's actually much more interesting than the summary, so I thank you for leading me there. It seems the study was performed by extracting data from the East Flanders Prospective Twin Survey performed in Belgium on 310 pairs of twins between 7 and 15 years old. From the study:
"Mixed modeling was performed to investigate green space in association with intelligence and behavior while adjusting for potential confounding factors including sex, age, parental education, neighborhood household income, year of assessment, and zygosity and chorionicity."
So although they didn't have a direct measure of parent IQ, they attempted to account for it by assuming education+neighborhood = IQ. (A reasonable assumption, although one wonders in this era of social unrest if such a claim might be considered "racist"?)
The study also makes this statement:
"Children in low green areas are more likely (4.2% versus 0%) to have a total IQ of 80 or lower. Furthermore, although 11.9% of those living in a green area had IQ scores in the superior range (>125), only 4.2% of the children living in a low green area had scored in this range."
Maybe it's in there somewhere but what I couldn't find in the study is how many points were added or subtracted from the low-green versus high-green areas to bring them on an equal footing so the "greenicity" might be visible. That is, how much of the IQ difference is not due to green areas. But an interesting read and thanks again for steering me to the source.