From tomshardware Kindle Owners Older and Richer Than iPad Owners
Nielsen recently conducted a study of 5,000 people who already own a tablet, ebook reader, netbook, media player or smartphone and found that, despite the iPad's higher price tag, Kindle users are richer than those willing to fork out for an iPad. According to Nielsen's survey, 44 percent of them make more than $80,000/year compared to 39 percent of iPad owners and 37 percent of iPhone owners.
Nielsen also found that iPad owners tend to be younger and male; 65 percent of iPad owners are male, while 63 percent are under the age of 35. When it comes to the genders of Kindle owners, it's nearly half and half, with 52 percent of owners being male, and 48 percent being female.
Nielsen also mentioned that Kindle owners are better educated with 27 percent having Master's degrees or doctorates, but failed to give any statistic for iPad owners.
The original source is Nielsen, and it also reports that iPad owners are for some reason far more receptive to online advertising than general computer users.
The Connected Devices Age: iPads, Kindles, Smartphones and the Connected Consumer | Nielsen Wire