I am a UCLA alumnus, and I get their monthly alumni newsletter. I wanted to point you guys to a UCLA study because I think we need to more closely examine the theory of "The surge has worked. Senator McCain was right. Senator Obama denies it." I am by no means casting any doubts on the bravery of our troops.
Link to UCLA Study
By tracking the amount of light emitted by Baghdad neighborhoods at night, a team of UCLA geographers has uncovered fresh evidence that last year's U.S. troop surge in Iraq may not have been as effective at improving security as some U.S. officials have maintained.
Night light in neighborhoods populated primarily by embattled Sunni residents declined dramatically just before the February 2007 surge and never returned, suggesting that ethnic cleansing by rival Shiites may have been largely responsible for the decrease in violence for which the U.S. military has claimed credit, the team reports in a new study based on publicly available satellite imagery.
Link to UCLA Study
Ths study also states:
By contrast, the night-light signature in the notoriously impoverished, Shiite-dominated Sadr City remained constant, as it did in the American-dominated Green Zone. Light actually increased in Shiite-dominated New Baghdad, the researchers found.
The authors seem to think that the decline in violence might be because the intercommunal violence had reached its climax at the beginning of the surge, rather than because of the surge.