Both ad impressions and ad clicks increased--by 51% and 66%, respectively.
The 2013 holiday season competition powered a reversal in advertising unit cost trends from Q3. Cost per impressions for Facebook advertising increased by 33% in Q4 of 2013. Another interesting fact is that direct response advertisers continue to see strong performance from their paid social campaigns.
SOURCE: Kenshoo Social, 2014, Facebook Advertising Key Performance Indicators Spike in Q4 2013 for Kenshoo Social Clients