Assessing the degree of urbanisation using a single-item self-report measure: a validation study.

The differential impact of rural versus urban residence on mental health remains a controversial topic that requires more in-depth investigations. This calls for a valid and easy measure to assess the degree of urbanisation. The purpose of the present study was to determine the utility of a single-item self-report measure (SIDU) as a tool to classify areas along the rural-urban continuum. The validity of the SIDU was assessed by comparing its scores (1-7) to a commonly used objective surrogate measure of the degree of urbanisation (i.e. surrounding address density, SAD) in two independent older adult samples (A: N = 36, 65+; B: N = 121, 55+). SIDU scores approximated SAD scores, with r = .77 to 0.82, (A), and r = .79 to 0.83 (B). A SIDU threshold score of 6 most accurately distinguished extremely urbanised areas from other areas. Altogether, our findings suggest that SIDU scores could be used as proxy of SAD. Since self-report leaves room for the consideration of additional aspects that confer an urban settlement, this single-item scale may be even more comprehensive, and circumvents the collection and handling of highly sensitive location data when the primary goal is solely to distinguish urbanisation subgroups.