With Comcast charging penalties to some of its customers when they exceed monthly data limits, the cable company is trying to assure the public that it won't make mistakes when counting data. Comcast thus commissioned network performance consultancy firm NetForecast to test the accuracy of the meters.

Unsurprisingly, the tests came out in Comcast's favor. Since Comcast is paying for the study, it wouldn't have to authorize its release if the results were negative.

In any case, NetForecast's report (PDF) "details the cumulative accuracy results from 569,376 measurements at 55 Comcast service locations for the 3-month period of January through March 2014." It's the third such report, with the first two having been released in 2009 and 2010.

NetForecast performs its own traffic measurements separately from the results issued by Comcast's meters and compares the two.

"Comcast established an accuracy goal to measure traffic passing through a subscriber’s cable modem within plus or minus (+/-) 1% accuracy over a month," the report authors wrote at Network World. "Our analysis validates that Comcast exceeded its goal, with actual month-end accuracy ranging between -0.75% to +0.36%."

NetForecast performs two types of tests. In one, the firm "continuously count[s] all traffic into/out of the Internet connections of volunteers who opt into the meter accuracy assessment program and self-install specially instrumented, off-the-shelf routers. Passive measurements take place under real-world conditions—i.e., they rely exclusively on the subscriber’s home traffic."

In the second type of test, NetForecast "installs a test laptop PC running NetForecast software and the same specially instrumented router used for passive measurement on each Internet connection. We use FTP accounts on NetForecast servers on the Internet. Both downstream and upstream testing is performed under a variety of conditions." The tests "consist of repeatedly transferring files of varying sizes in complex patterns. Tests are also performed as uploads from the laptop to the server."

Comcast touted the results on its website.

Karl Bode of DSLReports wrote that the data—if reliable—could show that "Comcast [is] a step ahead of the abysmal meter reliability and accuracy that's now the broadband industry norm." Still, Bode argued that "'trusted third parties hired by the company doing the billing shouldn't be confirming meter accuracy, regulators should be. If ISPs want to bill like utilities, regulating them like utilities is the only way to confirm meter accuracy."

One DSLReports commenter raised a good point: "Meters should not take into account incomplete data transfers. If downloading a (huge) file is interrupted due to [a] crappy connection and has to [be] restarted, will the failed chunk count towards the bill?"

It's not clear from the report whether that is accounted for, but we've asked Comcast and the report author if it is and will update if we find out.

Regardless of the results, Comcast will have a tough time convincing customers that data meters and penalties for going over data allotments are a good thing. Time Warner Cable, which Comcast is trying to acquire, tried to tempt customers with discounts in exchange for giving up unlimited data plans—and almost no one took the company up on its offer.

In parts of its service area, Comcast has rolled out 300GB data caps—though Comcast insists that they're not "data caps" since customers can go over them. If customers do use more than 300GB, they're charged $10 for each extra 50GB.

Comcast Executive VP David Cohen recently speculated that the company could roll out its "usage-based billing model" across its entire footprint within five years. Cohen later said that Comcast will also consider offering unlimited data plans, which presumably would cost more.

The American Customer Satisfaction Index found last month that Comcast and Time Warner Cable are the most hated companies in the Internet service market, as well as in the subscription TV and fixed-line telephone service markets.