An Improved Measure for Exploring Sociospatial Inequalities in Access to Online Fresh Food

Access to fresh food is essential for promoting healthy diets, yet existing measures of online food access remain limited and often overlook socioeconomic disparities at fine spatial scales. This study develops an improved measure of online food accessibility that accounts for consumer purchasing behavior at varying distances. It adapts the enhanced two-step floating catchment area (E2SFCA) method using an empirically derived, nonmonotonic distance impedance function. This behaviorally grounded approach reflects real-world dynamics, where consumers are less likely to use delivery services at very short or long distances. Using Shanghai as a case study, this study evaluates accessibility to supermarkets, grocery stores, and fruit stores. Socioeconomic disparities in access to online fresh food retailers are then examined through spatial error models with spatially lagged responses. Results show that areas with higher proportions of older adults have greater access, whereas those with more low-income residents experience significantly lower accessibility. No significant associations were found for gender or car ownership. Built environment features, including density and the number of physical food outlets, also influence online accessibility levels. By integrating the E2SFCA framework with real-world delivery data, this study improves the measurement of online food access and reveals emerging inequalities in the digital food environment, offering insights for equitable and health-oriented urban planning.