How Did Free Wi-fi Help Unlock Hanoi Wet Markets’ Mysteries?

Researchers at the Alliance of Bioversity International and CIAT and their collaborators have been working on how to harness the power of the estimated 549 million Wifi hotspots worldwide, resulting in a project that used anonymized data gathered from free Wi-Fi to better understand the impact of COVID-19 on Hanoi’s wet markets during the first stage of the Covid-19 pandemic.

In the paper “Using free Wi-Fi to assess impact of COVID-19 pandemic on traditional wet markets in Hanoi” published in December 2023 in the scientific journal Food Security, the researchers analyzed and interpreted mobile device tracking data from 25 Wi-Fi access points to characterize the changes in behavior in the users of hundreds of stores and food stalls across five wet markets in Hanoi, from July 2019 to November 2020.

Lead author Louis Reymondin, who co-leads the Data Driven Sustainability research theme for the Alliance of Bioversity International and CIAT says that by counting the number of individual device addresses within a certain range of the access points, the researchers got a sense of the number of people present (with the details of users anonymised).

“We recorded every phone within the vicinity of the access points every 2 minutes, and recorded 173,668,702 data points, filtered down to 13,238,809 useful data points, corresponding to 656,789 unique devices observed, ” Reymondin says.