Measuring Price Differentials in Food Retailing Joseph Llobrera Gerald J. Friedman Fellow in Nutrition and Citizenship

Food Environment Availability (also variety and quality) Affordability (budget constraints) Access (physical) –Individual or area Food deserts: area with limited access to affordable and nutritious food

Current methods Proximity, density of food stores Market Baskets –Thrifty Food Plan –Community Food Security Assessment Toolkit 87 food items –Nutrition Environment Measures Survey 10 food categories or food items

Significance Methodological choices –Selecting areas –Selecting retailers –Selecting foods –Missing values –Aggregating prices How to communicate and display detailed price information effectively and accessibly

Significance NCI/NIH 2007: robust measures are needed to assess effect of community food environment on individual diet ERS 2009: improved methods are needed to measure access levels, availability, and prices of foods faced by individuals and areas

Aims Aim 1: Determinants of food spending patterns Aim 2: Data collection method to measure food availability and price Aim 3: Modifications and extensions

Aim 1: Hypotheses Aim 1: Examine determinants of food spending patterns Hypothesis 1A: –Fulltime Employment --> fewer perishable or unprocessed foods (fresh fruits and vegetables or unprocessed meats) Hypothesis 1B: –Fulltime Employment --> different frequency and size of food purchases

Aim 1: Methods Consumer Expenditure Survey Diary Data –Detailed food expenditures Outcomes: –Food spending amount –Food shopping frequency

Aim 1: Methods Explanatory variables (X) Full-time employment Family size Number of children Vehicle ownership –Consumer unit control variables (Z) Income SNAP participation Race/ethnicity

Aim 1: Analysis Regression analysis –OUTCOME =  0 +  1 X +  2 Z + e

Aim 2: Hypotheses Aim 2: Develop data collection method to measure food availability and price Hypothesis 2A: Food availability is lower, while food prices are higher, in lower-income neighborhoods compared to higher-income neighborhoods Hypothesis 2B: Food availability is greater, while food prices are lower, at larger retailers compared to smaller retailers

Aim 2: Methods Select Geographic Units Select Food Retailers Select Food Items

Selecting Geographic Units

Selecting Retailers Source: SNAP Benefit Redemption Division, 2009 Annual Report

Selecting Food Items Test a few different methods and market baskets (including for Aim 3) Availability Lowest cost variety Highest cost variety Variety with most shelf space

Aim 2: Analysis Develop a food price index Compare price level using different market baskets –By neighborhood (hhd income level) –By type of retailer

Aim 2: Analysis

Aim 3: Hypotheses Aim 3: Modifications and extensions Hypothesis 3: The price premium for packaging and convenience varies more across neighborhoods than across retailer type.

Aim 3: Methods and Analysis Similar analysis to Aim 2 Different market basket depending on empirical question

Challenges/Limitations Cooperation and trust of smaller retailers Boston area only Mainstream food retailers Seasonality No household survey

Novel Contributions Rigorous, systematic and transparent method –Sampling methods –Use of weights Development of graphs, maps and other visual tools to show variability in food availability and price

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