Even during the presidential primaries it was obvious that traditional TV advertising wasn't working as well as it once did: Four Republican candidates were outspending Donald Trump but losing to him, and Bernie Sanders spent more on TV spots than Hillary Clinton. Now, with the general election campaign in full swing, the efficiency of TV ads remains in doubt.
The poll results from hotly contested states published since Sept. 15 show Donald Trump and Hillary Clinton within one to eight percentage points of each other; each candidate is leading in some of the battlegrounds. Libertarian candidate Gary Johnson is a distant third with varying levels of support -- 4 percent in Ohio and 14 percent in Pennsylvania.
Using spending data from Kantar Media's Campaign Media Analysis Group, I added up up the candidates' estimated TV ad expenditures between July 1 and Sept. 15 in nine contested states. I added in shares of national TV ad spending, weighting them by the states' population. On average, one percentage point in polls cost Clinton almost $214,000 during that period. Trump paid an average of about $60,000 per percentage point, and Johnson a mere $4,000.