This is derived from a data set in which the climate and tree cover
information were given for each half degree of latitude by half
degreee of longitude pixel.
The variable NoYes was given by administrative region.
The climate data and tree cover data given here are 50th or 90th
percentiles, where percetiles were calculates across pixels for an
administrative region.
References
Hales, S., de Wet, N., Maindonald, J. and Woodward, A.
2002. Potential effect of population and climate change global
distribution of dengue fever: an empirical model. The Lancet 2002;
360: 830-34.