Validas, a company that promises to "slash your cell phone bill, on average, by 20%," conducted the study, by examining over 55,000 cell phone bill from Verizon and AT&T in 2011.
The study showed that AT&T's alleged data hogs were not actually using much more data than anyone else. The study says that the top 5 percent of data users on AT&T's network use (on average) 3.97GB per month, only 780MB more than the top 5 percent of those that use tiered plans, which come in different flavors and prices.
In conclusion, the company says AT&T is throttling to force users over to their tiered plans, which are "easier to manage" and efficiently block the occasional user who does use a massive amount of data that actually puts a strain on their network.
Read the report here: Validas Blog