The Ad Wars: From every source, a different number

Tracking campaign ads in the 2012 elections is no easy feat. Between the flurry of spots from the Obama and Romney campaigns as the presidential race enters its home stretch, and the massive expenditures by outside groups such as super PACs, it is hard to get a handle on who is spending what to influence the nation’s biggest political decision. The confusion is being aggravated by another basic obstacle: that each major source of data on campaign ad spending provides widely different figures.