{"id":53,"date":"2012-05-20T12:55:30","date_gmt":"2012-05-20T16:55:30","guid":{"rendered":"http:\/\/notyourtypicalmaps.com\/?p=53"},"modified":"2012-12-18T13:03:27","modified_gmt":"2012-12-18T18:03:27","slug":"cartograms-are-evil","status":"publish","type":"post","link":"https:\/\/notyourtypicalmaps.com\/?p=53","title":{"rendered":"Cartograms are evil!"},"content":{"rendered":"

Cartograms are evil\u2026<\/p>\n

I recently engaged in a pretty heated debate with a senior researcher at my company about the merits and drawbacks of various data visualization techniques. \u00a0This particular person used mapping as a great example of visualization techniques, unfortunately started to focus his attention on cartograms (insert image here) as the best example of data visualization out there. \u00a0I nearly choked\u2026 \u00a0There is a fascination with cartograms that is bordering on fanaticism. \u00a0As we continued our conversation, I tried to articulate the pros\/cons of cartograms (mostly cons).<\/p>\n

What are cartograms?<\/h1>\n
There are many variations on the concept of cartograms, but in general the idea behind cartograms is to adjust the size of the shapes or objects on the map, using a pre-determined set of rules or algorithms to provide a new visualization of the world that we know.<\/div>\n

The problems with cartograms (or why\u00a0they are evil).<\/h1>\n

 <\/p>\n

There are three problems with cartograms that make them evil and (IMHO) useless and dangerous as a means of communication.<\/p>\n

    \n
  1. Assumption of geographic knowledge:<\/strong> \u00a0The most common cartograms deform the underlying geography so that the areas end up representing the proportions in the numbers. \u00a0For example, you could resize all states to represent electoral votes they have in the electoral college, and create a new map of the US where Alaska is tiny, California huge, the East coast fairly dominant, and the middle of the country fairly small. \u00a0These areas in the middle of the country have a lot of land, but not a lot of people, and thus have (generally) fewer seats. \u00a0This, as the example shows, is often used in showing national information in the US, but is also used to show global trends like the share of global GDP that every country has, etc\u2026 \u00a0The first problem is that most people don’t have a good sense of size and geography. \u00a0Do you know (at first reaction) how many times larger Alaska is then California? \u00a0If you did, do you get a sense of the impact of the electoral college is? \u00a0Most likely you’ll answer that you don’t know the relationship, but seeing California blow up like a balloon is a sign. \u00a0However, I’d argue that there this map does not give you anything more than a table that shows bar graphs for each state.<\/li>\n
  2. Projection issues & education:<\/strong> The second issue is that most cartograms are based on one form or another of cartographic project, and most people have been brought up on the Mercator project which renders areas closer to the pole much larger, and areas around the equator much smaller. \u00a0So our basis for comparison is often biased to start out with<\/li>\n
  3. Arbitrary Algorithms:<\/strong> I realize that this is an oxymoron, however, the algorithms prioritize relative scale, and physical proximity (i.e. New Hampshire, Vermont and Maine need to be side by side, and need to be above Massachusetts, which needs to be above Rhode Island and Connecticut. \u00a0As a result you got odd ballooning and squeezing effects which poorly reflect the reality of the underlying information. \u00a0For example, if you choose to represent something that is worth 100 units, you could choose to represent as a 10 by 10 square, or a line that .1 of a square wide, and 1000 units long. \u00a0This line could be barely perceptible at the same overall scale, and would then create the perception that the 10 by 10 could be larger.<\/li>\n<\/ol>\n

    Hope in Cartograms:<\/h1>\n

    The biggest hope in cartograms, I believe, is with those that use a known shape (a 1 by 1 square, or circle of radius of 1), and scale them up. \u00a0You can still keep the alignment mostly right, but then ensure that you are a) free of project, b) don’t have to assume that people know geography too well, and c) can be sure that two geographies worth 100 units are equally represented.<\/p>\n

    So why are they used so frequently:<\/h1>\n

    In short – sex appeal. \u00a0They are sexy, and make people pause for a second.<\/p>\n

    What do you think?<\/p>\n

    (link for more info on cartograms: )<\/p>\n

    http:\/\/www.ncgia.ucsb.edu\/projects\/Cartogram_Central\/types.html<\/p>\n","protected":false},"excerpt":{"rendered":"

    Cartograms are evil\u2026 I recently engaged in a pretty heated debate with a senior researcher at my company about the merits and drawbacks of various data visualization techniques. \u00a0This particular person used mapping as a great example of visualization techniques, unfortunately started to focus his attention on cartograms (insert image here) as the best example […]<\/p>\n","protected":false},"author":3,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","enabled":false},"version":2}},"categories":[55,39,56],"tags":[57,55,56,58],"class_list":["post-53","post","type-post","status-publish","format-standard","hentry","category-cartography","category-geography","category-mapping","tag-cartograms","tag-cartography","tag-mapping","tag-politics"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5yPko-R","_links":{"self":[{"href":"https:\/\/notyourtypicalmaps.com\/index.php?rest_route=\/wp\/v2\/posts\/53","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/notyourtypicalmaps.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/notyourtypicalmaps.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/notyourtypicalmaps.com\/index.php?rest_route=\/wp\/v2\/users\/3"}],"replies":[{"embeddable":true,"href":"https:\/\/notyourtypicalmaps.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=53"}],"version-history":[{"count":0,"href":"https:\/\/notyourtypicalmaps.com\/index.php?rest_route=\/wp\/v2\/posts\/53\/revisions"}],"wp:attachment":[{"href":"https:\/\/notyourtypicalmaps.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=53"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/notyourtypicalmaps.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=53"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/notyourtypicalmaps.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=53"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}