Your point is irrelevant. Some people got out of the lower brackets, some people got out of the higher brackets. So? How does that disprove the findings? We are talking about the expansion of income in the United States' economy from 1979 to 2007. The richest of us grew at an exponential rate compared with the poorest of us. An 18% increase for the bottom 20% over 28 years doesn't even keep up with inflation. Your point about upward and downward mobility does not effect in any way the findings of the study-which clearly shows that income increases in the lowe brackets has not even kept pace with inflations. It also shows what a bunch of horse manure "trickle down" theory is.