Network Evaluation Should Be Transparent

Several third-party firms collect data on the performance of U.S. wireless networks. Over the last few months, I’ve tried to dig deeply into several of these firms’ methodologies. In every case, I’ve found the public-facing information to be inadequate. I’ve also been unsuccessful when reaching out to some of the firms for additional information.

It’s my impression that evaluation firms generally make most of their money by selling data access to network operators, analysts, and other entities that are not end consumers. If this was all these companies did with their data, I would understand the lack of transparency. However, most of these companies publish consumer-facing content. Often this takes the form of awards granted to network operators that do well in evaluations. It looks like network operators regularly pay third-party evaluators for permission to advertise the receipt of awards. I wish financial arrangements between evaluators and award winners were a matter of public record, but that’s a topic for another day. Today, I’m focusing on the lack of transparency around evaluation methodologies.

RootMetrics collects data on several different aspects of network performance and aggregates that data to form overall scores for each major network. How exactly does RootMetrics do that aggregation?

The results are converted into scores using a proprietary algorithm.[1]

I’ve previously written about how difficult it is to combine data on many aspects of a product or service to arrive at a single, overall score. Beyond that, there’s good evidence that different analysts working in good faith with the same raw data often make different analytical choices that lead to substantive differences in the results of their analyses. I’m not going take it on faith that RootMetrics’ proprietary algorithm aggregates data in a highly-defensible manner. No one else should either.

Opensignal had a long history of giving most of its performance awards to T-Mobile.[2] Earlier this year, the trend was broken when Verizon took Opensignal’s awards in most categories.[3] It’s not clear why Verizon suddenly became a big winner. The abrupt change strikes me as more likely to have been driven by a change in methodology than a genuine change in the performance of networks relative to one another. Since little is published about Opensignal’s methodology, I can’t confirm or disconfirm my speculation. In Opensignal’s case, questions about methodology are not trivial. There’s good reason to be concerned about possible selection bias in Opensignal’s analyses. Opensignal’s Analytics Charter states:[4]

Our analytics are designed to ensure that each user has an equal impact on the results, and that only real users are counted: ‘one user, one vote’.

Carriers will differ in the proportion of their subscribers that live in rural areas versus densely-populated areas. If the excerpt from the analytics charter is taken literally, it may suggest that Opensignal does not control for differences in subscribers’ geography or demographics. That could explain why T-Mobile has managed to win so many Opensignal awards when T-Mobile obviously does not have the best-performing network at the national level.

Carriers advertise awards from evaluators because third-parties are perceived to be credible. The public deserves to have enough information to assess whether third-party evaluators merit that credibility.

Footnotes

  1. From RootMetrics’ Methodology web page on 5/3/2019 (archived here).
  2. Previous Opensignal reports related to U.S. networks can be viewed here.
  3. In Opensignal’s January 2019 report, Verizon won in four of five categories (one of the four wins involved a tie for the top spot).
  4. The excerpt comes from the Analytics Charter web page on 5/3/2019 (archived here).

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