• by Laurie Sullivan , Staff Writer @lauriesullivan, January 23, 2015

Marketers have a love/hate relationship with Facebook. Some search marketers say the social media site doesn't provide the return on investment, while others can't live without it. Numbers released this week from several sources tell an interesting tale. Apparently the market has reacted positively to the changes in user experience; mobile adoption domestically and abroad; and costs, especially when it comes to mobile and video.

Facebook drove most social media site traffic in Q4 2014 mong Merkle RKG clients. An agency report found that social media sites produced 2.4% of all site visits in Q4, up from 1.4% in the year-ago quarter. Facebook accounted for 62% -- up from 57% --  of all social media-driven visits. Other major social media sites saw flat or declining social visit share year-over-year, with YouTube declining the most from 2% down to 0.6%.

There's a catch to all the upside. The share of traffic being bucketed as social is depressed by what the industry calls "dark social" visits, visits from social media where the proper referrer string is not passed, leading to incorrect attribution. Message, email, and mobile app traffic all contribute to dark social, per Merkle RKG.

Interestingly, Macquaire Securities Analyst Ben Schachter published a research note Friday looking at Facebook's strategic roadmap. He specifically points to focus areas that have the potential to become large businesses in time. The social network's investments in these "very high-potential" areas are not likely to become meaningful drivers, but each hold the "potential to become transformative," he wrote. "We note that we are particularly bullish on FB's potential in search given the 1.5mm + advertisers already on the platform."

Mobile accounts for more than half of social media visits, per Merkle RKG. Some 52% of all site visits came from social media on tablets and phones in Q4, up from 37% in Q4 of 2013. Social media continues to outpace paid and organic search in the share of traffic coming from mobile devices. 

The cost-and-effect of doing business on the Facebook platform continued to post huge increases this past Q4, per 3Q Digital. The company crunches advertising numbers, more than 1billion impressions that occurred in Q4 and found a 364% year over year (YoY) increase in click-through rates (CTR), attributed to more advanced creative testing and the mainstream adoption of Custom Audiences.

3Q Digital also found an overall 35% YoY increase in cost per clicks (CPCs) comparing December 2013 to December 2014. Within the retail vertical, the company identified a 392% increase of CTRs, and that CPMs tripled YoY, more than doubling for mobile.