Research Article

A Wave-Spectrum Analysis of Urban Population Density: Entropy, Fractal, and Spatial Localization

Figure 4

Histograms of spatial ACF and PACF of Hangzhou’s population density (2000). The two lines in the histograms are called “two standard-error bands,” according to which we can know whether or not there is significant difference between ACF or PACF values and zero.
728420.fig.004a
(a) Spatial ACF histogram
728420.fig.004b
(b) Spatial PACF histogram