Last week mobile ad network inMobi released tablet survey findings, drawn from 9,600 respondents in seven international markets. US responses were just under 1,000 (904). The company asserts that "tablet use has risen quickly to 29.5 million U.S. users, 11% of the total U.S. population." 

By comparison, in January of this year the Pew Internet Project released survey data that showed 19% of US adults owned tablets (mostly iPads). And comScore released data showing that roughly 24% of smartphone owners also have tablets. If we extrapolate these numbers, the Pew data suggest that there are roughly 42 million tablet owners in the US (as of January 2012). The comScore data argue the number is closer to 56 million.

The inMobi number is too small, while the comScore number is probably too large. Pew is likely closer to the actual number of tablet users in the US at this point. However, by the end of the year it could be closing in on 70 million. 

The inMobi survey data are from a report entitled, The Role of Connected Devices in the Consumer Sales Journey. Below are some of the top-level findings: 

General consumption habits

• Over 60% of US tablet owners spend at least 30 minutes each day accessing media content on their tablets
• 52% use a tablet to fill what previously would have been “dead time.” 
• 29% of US tablet users said they have reduced reading books in print.
• 29% of tablet owners claimed they reduced surfing the internet via their PC and/or laptop.
• 48% of respondents agree that tablets’ appealing design and accessibility make it is easier to access media content than on a PC or laptop.

Shopping and e-commerce 

• 22% of tablet users claim they have shopped less in physical stores since purchasing a tablet
• 55% of tablet owners make purchases on their device in an average month. 

According to the survey data, "tablets have become the preferred device at home and smartphones are preferred on the go." These devices play different roles in the "purchase consideration cycle." Tablets are used in a "lean back" mode in the evenings and on weekends, almost exclusively at home. 

A recent tablet-centric e-commerce report from Monetate also observed that tablets are used primarily at home, as a PC substitute, and offered the following advice:

With increases in website traffic from devices such as the iPad and Kindle Fire, e-commerce businesses must treat customers using tablets as a unique audience segment. Tablet users expect a different experience that takes advantage of their devices’ features, such as touch/swipe functionality and screen rotation.

Accordingly it's not enough to simply assume the PC site will translate onto tablets. While non-flash PC sites often render relatively well on tablets they typically fail to take full advantage of the tablet opportunity.