In addition to disparities based on the community where a family lives and significant and persistent racial disparities, I have been struck while traveling around the country by the widening gulf between the economic fortunes of our large metropolitan areas and those of our small cities, towns, and rural areas.
Therefore, the natural rate has to be estimated indirectly based on current and past observations of directly observable economic data, making use of a more or less detailed model prescribing the interactions of the NRI with these variables.