Equity Illuminated: Navigating Urban Food Deserts Through Pricing Dynamics

By Subham Kharel, Soheil Sharifi & Qisheng Pan

Imagine you're standing in a Walmart, shopping for groceries. It's not just about convenience or preference; for many people, it's about affordability. Big-box stores like Walmart often provide more budget-friendly options than local farmers' markets. But there's a more significant issue beyond personal choice: accessibility. If you don't have a car, getting to these stores can be challenging. This is where fairness comes into play. Grocery chains strategically set up shop in locations optimized for their logistics, but this often leaves out people without cars or those living in areas without easy access to grocery stores, creating urban food deserts.

Our research aims to shed light on these complexities by focusing on people's disposable income and the pricing of food to measure accessibility. We look at how far individuals must travel to access different types of grocery stores, considering whether they have transportation or must rely on walking. Additionally, we examine the demand for various kinds of groceries and the level of supply, in each area. This comprehensive approach helps us grasp the intricate dynamics of food access in various neighborhoods.

When discussing equity in food access, we use various tools to compare different groups. One key tool is the Gini Coefficient, which measures how evenly a resource is distributed within a population. A Gini Coefficient of 1 signifies extreme inequality, where one individual possesses everything, while everyone else has nothing. Conversely, a coefficient of 0 indicates perfect equality. However, the Gini Coefficient alone only provides a picture of how resources are distributed within a single population, ignoring inequalities between subpopulations. To address this limitation, we use the Accessibility Share to Population Share (AS/PS) Ratio. This measure allows us to compare inequality between clusters of subpopulations. By ensuring that the weights for both population and accessibility shares for the entire population add up to one, the AS/PS Ratio provides a clearer understanding of how accessibility is distributed across different groups.

Imagine Neighborhood A is predominantly White, and Neighborhood B is predominantly African American. Suppose Neighborhood A has a Gini Coefficient of 0.9 and an AS/PS Ratio of 1.2, while Neighborhood B has a Gini Coefficient of 0.3 and an AS/PS Ratio of 0.8. Despite Neighborhood B having a much lower Gini Coefficient, i.e., a better situation of equity, it still has worse access to grocery stores. On the other hand, although Neighborhood A has higher access to grocery stores, some groups in Neighborhood A have worst equity outcomes than other groups in the same neighborhood. This example underscores the importance of considering both the Gini Coefficient and the AS/PS ratio to gauge equity accurately.

To locate food deserts – areas where people struggle to access affordable food – we look for densely populated urban areas where many people live close together. Within these areas, we use our food access measure to see how easy it is to walk to a low-price grocery store. If it takes a long time to walk there and people in the area don't have much money to spend, we might have found a food desert.

Our study uncovers intriguing insights into the dynamics of food accessibility. While African Americans, Hispanics, and Asians share similar ranges of Gini coefficients, suggesting some level of parity in food resource distribution within their communities, the AS/PS ratio tells a different story. Asians had remarkably high AS/PS values, even surpassing Whites, indicating superior access to food. Conversely, African Americans and Hispanics lag behind, with very low AS/PS values, signaling a concerning disparity in access. This shows that even when resources appear to be equally distributed within a particular group, disparities can still exist when compared to other groups, and vice versa. It underscores the complexity of equity issues and the importance of considering multiple dimensions of accessibility when addressing inequalities.

What’s even more concerning is that we found food deserts overlapping with minority communities. This finding highlights the stark, systemic disparities these communities face regarding affordable food access. These food deserts often result from historical and ongoing inequities in urban planning, economic investment, and access to transportation, which disproportionately affect minority populations. The overlap underscores the urgent need for policies and interventions that specifically target these areas to address the deep-rooted causes of food insecurity and promote equitable access to nutritious and affordable food for all communities.

In conclusion, integrating measures such as the AS/PS ratio alongside traditional metrics like the Gini Coefficient is essential for building a more equitable food system that promotes the health and well-being of all communities, regardless of their economic status or location. By fostering a comprehensive understanding of food accessibility challenges, we can develop strategies to promote equitable access to nutritious and affordable food for all, fostering resilience and sustainability in our food systems.

About the Article
Examining Food Access Equity by Integrating Grocery Store Pricing into Spatial Accessibility Measures
Subham Kharel, Seyedsoheil Sharifiasl & Qisheng Pan
First published July 30, 2024
DOI: 10.1177/03611981241254382
Transportation Research Record: Journal of the Transportation Research Board

About the Authors