Free WiFi to monitor flow in Hanoian traditional markets

Despite being the main source of fresh, convenient, and affordable food for 80% of Hanoi’s population, food flows within traditional markets remain largely invisible due to a lack of tracing systems and environmental conditions which make traditional tracking approaches challenging. By providing free internet to a series of wholesalers and markets in the Cau Giay and Dong Anh districts of Hanoi, Vietnam, this project will put in place the first pieces of tracking system that will characterize and monitor food flows between traders, retailers, and consumers. Research has found that 10-40% of traditional market food is contaminated with microbes or parasites which cause foodborne illnesses. As shoppers become increasingly concerned about food safety and large-scale retailers that can offer food safety certification expand rapidly, this project aims to equip traditional market actors with data that could prevent their marginalization through urban policy decisions that may favor organized retailers, as well as improve the safety of traditional market goods. The collected food flow data will allow for improved linkages among key traditional market actors and help identify better policy and planning options for improving distribution channels in ways that benefits under-resourced communities. To implement the project, the Alliance of Bioversity International and CIAT and the General Statistics Office (GSO) of Vietnam survey actors and track space and time data points on all devices within the range of the WiFi routers and signal amplifiers, whether connected to the internet or not. The pilot system ran on three layers of data: Layer One Every smartphone has a unique media access control (MAC) address that the WiFi routers installed in the markers use to identify how many MAC addresses visit the markets over time, how many return to the market and how often, and how markets differ on these metrics. This data is collected even if the smartphone is not connected to the WiFi network. Layer Two When a smartphone user connects to the free WiFi, they are prompted to answer a series of questions depending on their user type (vendor, customer, etc.). For example, a user that identifies as a vendor is asked questions regarding sales of specific commodities which will allow for sales to be characterized across time and space. Layer Three To validate findings in Layer One and Two, in-person surveys were conducted with vegetable, pork and rice sellers in five traditional markets in Hanoi mac: An anonymized version of the MAC. All the MAC address were anonymized through a SHA-3 256 hashing function. The hashed mac ensure anonymity while is consistent across all markets and during the whole period of the analysis. We can therefore ensure that a given mac found in two different dataset will correspond to the same phone. market: The name of the market where the phone was seen role: Self-identified role if the user connected to the wifi and filled-out the layer 2 form gender: Self-identified role if the user connected to the wifi and filled-out the layer 2 form median_first_seen: The median time when the user is first seen in the markets (in minutes starting at 0 from midnight) (e.g. the time the user entered the market) median_last_seen: The median time when the user is last seen in the markets (in minutes starting at 0 from midnight) (e.g. the time the user left the market) average_time_day: The average number of time the user visited the market. A period of time of at least 2 hours between two consecutive observation of the user in the market is needed to be counted as a different visit. average_duration_day: The average duration spent on the market daily. average_day_week: The average number of visits per week. average_total_day_seen: The total number of days a user was seen on the market. total_durantion: Total duration spent by a single user on the market.尽管河内80%的人口均将传统市场作为新鲜、便捷且平价食品的核心供应渠道，但由于缺乏有效的食品溯源系统，且传统跟踪方法受当地环境限制难以落地，传统市场内部的食品流通轨迹在很大程度上仍处于不透明状态。本项目通过为越南河内市纸桥郡（Cau Giay）和东英郡（Dong Anh）的一批批发商与传统市场提供免费无线网络，搭建首套可刻画并监测商贩、零售商与消费者间食品流通链路的溯源系统雏形。 研究显示，河内传统市场中10%至40%的食品被可引发食源性疾病的微生物或寄生虫污染。随着消费者对食品安全的关注度持续提升，且可提供食品安全认证的规模化零售商快速扩张，本项目旨在为传统市场经营主体提供数据支撑，以避免其在偏向连锁零售商的城市政策决策中被边缘化，同时提升传统市场食品的整体安全水平。 所采集的食品流通数据可强化关键传统市场经营主体间的协同联动，并助力优化分销渠道的政策与规划方案，以此惠及资源禀赋不足的社区群体。为推进本项目，国际生物多样性联盟（Bioversity International）与国际热带农业中心（CIAT）联合越南统计总局（General Statistics Office, GSO）对市场经营主体开展调研，并追踪WiFi路由器及信号放大器覆盖范围内所有设备的时空数据点，无论这些设备是否连接互联网。 该试点系统基于三层数据架构运行： 第一层数据：每台智能手机均拥有唯一的媒体访问控制（Media Access Control, MAC）地址，部署于市场的WiFi路由器可通过该地址识别不同时段到访市场的MAC地址总量、重复到访的地址数量及到访频率，以及不同市场在上述指标上的差异。即便智能手机未连接WiFi网络，仍可采集此类数据。 第二层数据：当智能手机用户连接免费WiFi时，系统将根据其用户身份（商贩、消费者等）推送针对性问卷。例如，身份为商贩的用户将被问及特定商品的销售相关问题，以此实现不同时空维度下的销售情况刻画。 第三层数据：为验证第一层与第二层数据的有效性，研究团队对河内五家传统市场的蔬菜、猪肉及大米商贩开展线下调研。 ### 字段说明 1. **mac（MAC地址）**：经匿名化处理后的媒体访问控制地址。所有原始MAC地址均通过SHA-3 256哈希函数完成匿名化转换，经哈希处理后的MAC地址可保障用户匿名性，且在所有市场及整个分析周期内保持一致，因此可确保在两个不同数据集内出现的同一哈希MAC地址对应同一台手机。 2. **market（市场名称）**：检测到该手机的传统市场名称。 3. **role（用户身份）**：连接免费WiFi并填写第二层问卷的用户自行申报的身份类型。 4. **gender（性别）**：连接免费WiFi并填写第二层问卷的用户自行申报的性别。 5. **median_first_seen（首次到访中位时间）**：用户首次被检测到出现在市场的中位时间（以午夜起算的分钟数为单位，例如用户进入市场的时间）。 6. **median_last_seen（末次到访中位时间）**：用户末次被检测到出现在市场的中位时间（以午夜起算的分钟数为单位，例如用户离开市场的时间）。 7. **average_time_day（日均到访次数）**：用户日均到访市场的次数。两次连续检测到用户在市场的到访记录间隔需至少2小时，方可计为一次独立到访。 8. **average_duration_day（日均停留时长）**：用户每日在市场的平均停留时长。 9. **average_day_week（周均到访次数）**：用户每周平均到访市场的次数。 10. **average_total_day_seen（累计检测天数）**：用户在市场被检测到的总天数。 11. **total_duration（累计停留时长）**：单用户在市场的总停留时长。