Here's a link to Metrico's site discussing the outline of the report. Presumably the full report is only available to certain organizations and/or at some cost. I'd be curious to see the methodology as well.
However my own experience traveling across the country with both Verizon and AT&T 3G devices has shown the coverage gap between the carriers to be getting smaller and smaller over the past 3-4 years, to the point that I recently gave up my Verizon modem and only use my AT&T iPhone (with tethering). It's so rare to get a poor AT&T signal any more that I couldn't even remotely justify the cost of both.
I think the big shocker is how badly Sprint did. Slowest data speeds, highest call failure data rate. And prior to this they claimed to be the one with the best data network, and best capable to handle smartphones like this.
Well, okay, it's not really a shocker. I left Sprint in 2006 because data, voice AND customer service were so bad. It's just sad that clearly nothing has changed in 5 years.
And I agree, we need to know where the tests were conducted. Sprint is actually not-so-bad in the Southwestern part of the US, where their network was built out by the former Alamosa PCS. Back in the day, Sprint farmed out most of their non-metro regions to "affiliate" carriers, basically smaller wireless companies that used the Sprint brand, phone models and back-end, but built out the network and staffed the stores in their regions. Some affiliates were better than others, and Alamosa ran their network even better than Sprint ran its own company-owned portions.
All of the affiliates were bought up as part of the Nextel merger, and then it was universally downhill from there.
Lastly: I'm on AT&T now and never happier. I use voice and data simultaneously, and losing that is not worth the "extra" reliability on Verizon.
We had AT&T for the 2 year contract plus a few months after that was fulfilled, it wasn't the coverage that prompted us to leave, it was the unpredictable billing...it was never the same and seemed like it was always increasing every month. After switching to Verizon the bills been the same for these past 6 months we've been with them. I like that, I like knowing what my upcoming bills will be.