The FCC is taking a survey of broadband speeds, citing evidence that speeds are slower than providers advertise.

Well, comScore–the research firm that provided the FCC’s data–may not have used the best methods for gathering broadband speed data, making connections appear slower than they actually are.

Netforcast has uncovered several errors in comScore’s testing methodology that create lower broadband speed results. Those errors include the fact that most broadband connections are shared via wi-fi, with many systems and devices within a home accessing a broadband connection simultaneously. If one of those systems is using the broadband connection at the same time as comScore’s testing, a lower speed would result due to the sharing of the broadband connection. comScore’s tests do not compensate for this variable.

The comScore testing also “severely limits the accuracy of its results” because it only uses a single TCP connection for each test. Netforcast contends that most speed testing services use multiple TCP connections.