Sandberg pointed to the seismic mobile shift in 2013—the first year people spent more time on mobile than on TV.
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Facebook "made a huge investment in newsfeed ads," she said, referring to those tailored to stream in mobile apps. "Marketers want to be where people are—that's driving mobile results."
Ebersman said, "The most important number for us is the 76 percent growth in ad revenue versus last year—a very strong data point that Facebook advertising works. We're seeing returns from all the investments we're making in great mobile products to attract users."
The ability to measure results is also driving growth, the executives said.
"If you look back four to five quarters ago, we couldn't prove to marketers that we were ringing the cash register," Sandberg said. "We couldn't say, 'Here's the difference in sales.' " Now, she added, the investment in measurement is paying off, and Facebook can prove results both in-store and online.
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She said a French campaign for Coca-Cola's polar bears had a return on investment 3.6 higher than TV, and Facebook drove 27 percent of Coke's incremental sales.