Watchdog reporting on the ad wars depends upon a simple concept that has recently returned to fashion: arithmetic. It loses its teeth when the numbers don’t add up.

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“The Ad Wars: How do we cover them?”

“For TV, campaigns create big winners and (relative) losers”

“Where to Turn When Tackling Money-in-Politics Stories”

“The Top Campaign Finance Tools for Local News Sites”

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Sasha Chavkin covers political money and influence for CJR's United States Project, our politics and policy desk. He has written for ProPublica, the Center for Public Integrity, and The New York World. Follow him on Twitter @sashachavkin.