• by Laurie Sullivan  @lauriesullivan, February 8, 2012

Clicks on tablet ads from paid-search campaigns rose five times higher in January compared with the same period a year ago, according to research released Wednesday from Rimm-Kaufmann Group (RKG), a digital marketing agency.

Not all tablets generate the same click rate. Apple's iPad generates the majority of tablet traffic, with an 88% share, while Amazon's Fire managed to step in as a low-priced alternative, generating slightly more than 4% of tablet ad clicks in late December before dropping to 3.5% at the end of January.

The traffic from non-iPad tablets still comprises less than or around 1% of total traffic for most. In January, RKG estimates the traffic at 0.8%. 

About 68.1 million tablet units shipped worldwide in 2011, up from about 19.6 million in 2010 worldwide, according to the IHS iSuppli Worldwide Tablet Market Tracker Q1 2012. The research firm estimates tablet manufacturers will ship an estimated 124 million units in 2012.

Analyzing conversion metrics across tablets, phones and desktop, RKG found that clicks from shoppers using the Kindle Fire were far less valuable in January than those from users on almost any other device.

When it came to generating revenue per click (RPC), the Kindle Fire ranked worse compared with all other tablets and iPhone. RPC for Fire came in at 83% lower than desktop and 84% lower than the iPad. Ironically, Fire runs a version of Google's Android operating system (OS), but still fared poorly compared with other Android tablets, which could not hold up as well to desktop computers or the iPad.

RKG found greater variance in conversion rate than average order value. The AOV for the Fire came in at 28% lower than for desktop, but had a 76% lower conversion rate.  Both metrics put Amazon's tablet closer to a typical Android phone than an Android tablet.

RKG believes Kindle's performance suffers, in part, because of its smaller screen size, which makes it more challenging to make online purchases. Users are likely less affluent than those who own the iPad. The analysis points to comScore's findings that owners of the iPad have a yearly salary of more than $100,000, so owners are more likely to make frequent purchases.

Size is one feature the Amazon Fire has in its favor, other than costing a fraction of the iPad. Tablet owners are more inclined to take the Fire with them. But Amazon loses money on Fire -- about $3 per unit, the company said in its Q4 earnings report.