Maybe someone has access to the study and can find if there is even a number in the abstract.
I suspect you won't find a number until you get to the data section and that the variance of interest will be in the low double digits.
Anyone want to lay odds on the chance that it is actually in the single digits...
I think these studies fall under the "Broken window fallacy" of economics.
The broken window fallacy is the belief that if a persons window is broken and he has to get it replaced, that it is good for the economy because that means that the window fixer gets business, the glass company gets business therefore money is kept circulating. The fallacy here is that the money could have gone to things that were more productive instead of fixing things that would remain useful for long periods of time had they not been broken. Fixing the window is sending money to entropy. Inefficiency..