The Age Friendly Supermarket Index: a Delphi study and psychometric analysis.

BACKGROUND AND OBJECTIVES: Person-environment interactions shape how individuals evaluate their surroundings, and perceived age friendliness influences intentions to age in place. Supermarkets, as essential components of daily urban life, play a critical role in supporting older adults' community participation. This study aimed to develop and validate the Age Friendly Supermarket Index (AFSI), a comprehensive tool to assess and enhance supermarket age friendliness for older customers. METHODS: Indicators were generated through a literature review, followed by two Delphi rounds, cognitive interviews, and pilot testing. The AFSI was validated using survey data from 387 older adults in Macao. RESULTS: The finalized AFSI includes 33 indicators across three domains: (i) environmental design and customer service, (ii) convenience and safety assurance, and (iii) product arrangement and aisle planning. Exploratory and confirmatory factor analyses supported a three factor structure. The overall index showed excellent internal consistency (Cronbach's α = 0.93), with strong reliability across domains (α = 0.90-0.92), explaining 54.96% of variance. Measurement invariance was confirmed across gender, age groups, and living status. CONCLUSION: The AFSI is a reliable and valid instrument for evaluating supermarket age friendliness and can guide improvements to support age-friendly shopping environments.