Smallpox and Season: Reanalysis of Historical Data
Figure 4
The spectral density plots
for of smallpox. The spectral density plots for the
estimated reproduction numbers of smallpox in (a) the entire Netherlands, 1870–1873 and (b)
Northwest frontier province, India, 1890–1921. Compared
with Figures 2(d) and 2(e), the spectral densities clearly indicate a sharp
peak at a period of 12 months.
