Petraeus massages the data

Petraeus will claim a 75% reduction of violence since the surge started and will use multiple cherry-picked statistics to spin the White House's case. How did they cook the books?

For starters, they changed the definition of violence:
The Los Angeles Times reports that people killed in car bombings don't count.¹
The Washington Post reports that victims shot in the face don't count.²
The Center for Strategic and International Studies reports that Shi'a vs. Shi'a and Sunni vs. Sunni violence doesn't count.³