Tablet search ads have higher conversion rates than mobile, and lower CPCs than desktop

"Advertisers investing in search ads through Marin Software and IgnitionOne spent more on tablets compared with smartphones during the fourth quarter of 2012, despite comScore's estimate that 120 million U.S. consumers own smartphones, up from 30 million in the past year.
Combined, smartphones and tablets accounted for a 22% share of clicks and 17% share of spend, according to Marin Software's quarterly study, Global Online Advertising Trends, released Thursday.
It turns out that tablet search ads have a higher conversion rate compared with smartphones, and a lower cost-per click in comparison to desktop ads, making them an attractive investment. Prior to the fourth quarter of this year, investment in tablet advertising had lagged that of smartphones. Now companies see a boom for search ads on tablets.
For Marin clients, click-through rates (CTRs) on tablets in the U.S. were 2.85% during Q4 2012, with a cost per click (CPC) of about $0.67. CTR on smartphones were 4.34%, with a CPC of $0.49. U.K. search marketers also spent more on tablet devices as a percentage of their total budget.
Mobile devices accounted for a 23% share of clicks and a 17% share of spend for the fourth quarter in the United Kingdom. Click-through rates (CTRs) on tablets in the U.K. were 3.58% during Q4 2012, with a cost per click (CPC) of about 0.29 pounds. CTR on smartphones were 5.55%, with a CPC of 0.15 pounds."

Source:  MediaPost, 10th January 2013