FIGURE 3. Relationship between standardized log malaria annual incidence and summer precipitation for Botswana.
From the following article:
Malaria early warnings based on seasonal climate forecasts from multi-model ensembles
M. C. Thomson, F. J. Doblas-Reyes, S. J. Mason, R. Hagedorn, S. J. Connor, T. Phindela, A. P. Morse and T. N. Palmer
Nature 439, 576-579 (2 February 2006)
doi:10.1038/nature04503

Standardized log malaria annual incidence (per 1,000 population) versus November–February CMAP precipitation for the period 1982–2002 as obtained from fitting a quadratic function to observations4. The quadratic function is y = -8.9 + 5.9x - 0.8x2, where x denotes precipitation (measured in mm day-1) and y the standardized log malaria incidence index. The horizontal and vertical dotted lines denote the quartiles of the standardized log malaria incidence index, and precipitation, respectively.
