Walk Score discrepancies: address-based and postcode-based analysis in urban and suburban/rural contexts

Walk Score is widely used in urban design, real estate, and health research to assess neighbourhood accessibility and measure walkability. However, differences in address sources, such as postcodes and specific addresses, can lead to variations in Walk Score values. This study compares Walk Score outputs based on postcodes and full residential addresses. A secondary analysis was conducted using data from a larger epidemiological survey covering five study areas in Japan, including urban and suburban/rural areas. Walk Score was analysed using both continuous and categorical variables. Differences and agreements between postcode-based and address-based Walk Score values were examined using Wilcoxon signed-rank test, Spearman’s correlation coefficient, and Bland-Altman analysis. A total of 2205 cases were analysed. Statistically significant differences were observed between postcode-based and address-based values in both urban and suburban/rural areas. Among cases classified as Somewhat walkable using address-based scores, postcode-based scores assigned 66.7% to higher categories in urban areas and 39.6% to lower categories in suburban/rural areas. The correlation between the two data sources was moderately positive in urban areas and strongly positive both overall and in suburban/rural areas. These findings suggest that the postcode-based Walk Score may serve as an alternative method when address data are unavailable, but substantial misclassification in mid-range categories warrants cautious interpretation.