"It's data, but it's self-selected data, and so it's not really useful for the purposes of policymaking," Turner said. "Anecdotes matter in the public policy debate, but when you can get actual empirical data, policymakers should strive for that."

Though consumers run Speedtest by choice, the size of Ookla's sample should make it fairly representative, Apgar said. About 60 percent of the people running tests each month are first-time users of Speedtest, so it's not the same small group of users testing their lines over and over, he said.

"It can't serve as the only way to determine what the state of broadband is in the U.S. .... (but) it would be foolish to overlook a resource like this," Apgar said.