Population Density Gradients and Urbanisation Measurement

The exponential density function has been used widely to describe and compare the patterning of urban population. In this article it is argued that the exponent within the function can be biassed by the misidentification of the CBD and of the centroids of census tracts. Using a least-squares method it is shown that such misspecification (of the location of the CBD) leads to an underestimation of the gradient, and shows that the magnitude of the bias is itself related to the extent of the distance error by which the CBD is misidentified.