How does I3 geolocate NDT data?


How is the M-Lab NDT data geolocated?

The new I3 features for school districts are amazing, but I haven’t yet found an explanation of how I3 geolocates the speedtest data by school district. I’m pretty new to broadband research, but my understanding is that accurate geolocation is hard to do, especially for such small geographic units. Just wondering how I3 approached this problem.

Thank you! This is a terrific tool!

Hi Johnny!

Welcome to I3, the I3 Telegraph, and thanks for a taking time to ask an important question!

Here’s what the I3 does with the geolocation data from Measurement Lab:

  1. I3 starts with the test data provided by the Measurement Lab (M-Lab). Measurement Lab uses the MaxMind database to map internet addresses to points on the map. When a test is recorded in the M-Lab database, the client’s IP address is looked up in MaxMind to find the location associated with the IP address. This physical address is often associated with the Internet provider’s or large businesses local infrastructure rather than a specific residence or business address. So when you run a test from your home or business, the point on the map found via geo-location may not be the point where you ran the test.

This imprecision is not restricted to Measurement-Lab; most IP address geo-location methods exhibit similar behavior. Having anything more precise can create privacy issues. As a result, projects like the Michigan Moonshot, or the M-Lab Piecewise tool, collect and protect actual test location data (with user agreement) without storing that data in the public M-Lab database.

  1. For States and Territories, I3 uses the State (aka “region”) code provided by M-Lab. For all the other areas, like a school district, I3 then selects the raw data points that actually lie within the school district (or other) boundary. Since I3 has the geographic boundary file handy, running the code to check that a point lies within a boundary could be automated.

As a result, I3 is conservative in ascribing M-Lab tests to localities smaller than a US State or Territory.