Cartogram or Mapograph: 

Statistical maps are also used to represent data like density of population indifferent states in the country or different countries in the world or the distribution of rainfall etc. They are usually used to depict the  quantitative  facts on regional or geographical basis.  Cartograms are simple and elementary forms   of visual presentation and are very easy to understand. While highlighting the regional or geographical comparisons, comparisons, mapographs or cartograms are generally used.