Caspi Caitlin Eicher, Friebur Robin
Department of Family Medicine and Community Health, University of Minnesota, Program in Health Disparities Research, 717 Delaware St. SE, Minneapolis, MN, 55414, USA.
Nutrition Policy Institute, University of California Berkeley, 2115 Milvia Street, Suite 3, Berkeley, CA, 94704, USA.
Int J Behav Nutr Phys Act. 2016 Mar 17;13:37. doi: 10.1186/s12966-016-0360-3.
A major concern in food environment research is the lack of accuracy in commercial business listings of food stores, which are convenient and commonly used. Accuracy concerns may be particularly pronounced in rural areas. Ground-truthing or on-site verification has been deemed the necessary standard to validate business listings, but researchers perceive this process to be costly and time-consuming. This study calculated the accuracy and cost of ground-truthing three town/rural areas in Minnesota, USA (an area of 564 miles, or 908 km), and simulated a modified validation process to increase efficiency without comprising accuracy. For traditional ground-truthing, all streets in the study area were driven, while the route and geographic coordinates of food stores were recorded.
The process required 1510 miles (2430 km) of driving and 114 staff hours. The ground-truthed list of stores was compared with commercial business listings, which had an average positive predictive value (PPV) of 0.57 and sensitivity of 0.62 across the three sites. Using observations from the field, a modified process was proposed in which only the streets located within central commercial clusters (the 1/8 mile or 200 m buffer around any cluster of 2 stores) would be validated. Modified ground-truthing would have yielded an estimated PPV of 1.00 and sensitivity of 0.95, and would have resulted in a reduction in approximately 88 % of the mileage costs.
We conclude that ground-truthing is necessary in town/rural settings. The modified ground-truthing process, with excellent accuracy at a fraction of the costs, suggests a new standard and warrants further evaluation.
食品环境研究中的一个主要问题是食品商店商业名录缺乏准确性，而这些名录方便且常用。在农村地区，准确性问题可能尤为突出。实地核实或现场核查被视为验证商业名录的必要标准，但研究人员认为这个过程成本高且耗时。本研究计算了对美国明尼苏达州三个城镇/农村地区（面积为564英里，即908公里）进行实地核实的准确性和成本，并模拟了一个改进的验证过程，以在不影响准确性的前提下提高效率。对于传统的实地核实，研究区域内的所有街道都要开车巡查，并记录食品商店的路线和地理坐标。
这个过程需要行驶1510英里（2430公里），耗费114个工作人员工时。将实地核实后的商店清单与商业名录进行比较，在这三个地点，商业名录的平均阳性预测值（PPV）为0.57，敏感性为0.62。利用实地观察结果，提出了一个改进过程，即只对位于中央商业集群内的街道（任何两个商店集群周围1/8英里或200米的缓冲区）进行验证。改进后的实地核实估计PPV为1.00，敏感性为0.95，并且里程成本将降低约88%。
我们得出结论，在城镇/农村环境中，实地核实是必要的。改进后的实地核实过程以极低的成本实现了极高的准确性，这表明了一种新的标准，值得进一步评估。
