Basic statistical understanding: Understanding variance, etc. Knowing when "New study shows apples cure cancer" is bullsh*t based on the other 900 studies that didn't find this, etc. Almost never seen here, maybe 4 or 5 posters capable of this, and most too lazy to bother much of the time as there's no reward.
Given the vast number of studies concluding that household recycling costs more than normal means of disposal, it's strange that you continue to cling to the exact opposition assumption.
Advanced understanding of systems theory and logical interaction in regards to human behavior. Extremely rare intuitive grasp of human nature coupled with extensive study of same and it's mathematical underpinnings to develop a system of analysis capable of understanding why people react a certain way to most situations, and frequently to predict same with reasonable accuracy in excess of randomness. - Me.
Hah! Funny how the first and last levels are more or less interchangeable depending solely on perspective.