Cartogram

Global population cartogram

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Levasseur cartogram

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Germany-population-cartogram

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PaullHennig2016WorldMap.OAha.CC-BY-4.0

Cartogram projector cz

Cartogram is a type of map used in geography and cartography that displays statistical data by transforming the sizes of geographic regions such as countries, states, or counties. Unlike traditional maps, where the area of each region corresponds to its actual geographical area, a cartogram distorts this area to reflect a specific dataset, such as population, economic output, or any other statistical measure. This method of representation helps to visualize the relative importance or proportion of the depicted data in a way that is immediately apparent to the observer.

Types of Cartograms

There are several types of cartograms, each with its unique method of representation and use cases. The most common types include:

• Area Cartograms: These adjust the size of the regions based on the data being represented. The most well-known example is the population cartogram, where the size of a country or region is proportional to its population.
• Distance Cartograms: These distort the map by adjusting the distances between points based on the data, often used to show travel times or connectivity.
• Density-equalizing Cartograms: Also known as Dorling or Demers cartograms, these represent regions using shapes like circles or squares, sized according to the data, but attempt to preserve the original geographic location as much as possible.

Creation

The creation of a cartogram requires specialized software that can algorithmically adjust the sizes of the regions based on the input data while attempting to maintain some semblance of the original geographic layout. This process can be computationally intensive, especially for detailed maps or complex datasets.

Applications

Cartograms are used in a wide range of fields including demography, public health, political science, and economics to visualize data in a way that emphasizes the relative importance of the regions over their geographical size. For example, in political science, cartograms can illustrate the distribution of electoral votes in a way that represents the population more accurately than a traditional geographic map.

Challenges

One of the main challenges in creating and interpreting cartograms is the balance between data representation accuracy and geographic recognizability. Highly distorted maps may accurately reflect the data but can become difficult to recognize or interpret. Additionally, the choice of which base map to use (e.g., a country's borders at a specific point in time) can influence the outcome and interpretation of the cartogram.

See Also

• Geographic Information System (GIS)
• Thematic map
• Topographic map