User:Kahlores/Sandbox/Choropleth maps

The case for Choropleth maps on Wikipedia election articles
Note: "Choropleth" means "cluster zones". A Choropleth map is a map that uses different hues of the same color, for the clustered variable. Typically, election maps on Wikimedia Commons and Wikipedia display the jurisdiction's constituencies ("districts", "ridings", "wards", etc.) colored by the party that won it. This makes perfect sense: under Plurality (First-past-the-post), whoever tops the district, gets the seat.

However, under the various forms of Proportional Representation, no-one "wins" a district: districts are multi-member, and coming first is no more meaningful than coming second, only the share of votes is (which by design gives the share of seats).

As a reminder, PR methods are in use in: (That is, in summary, most liberal democracies and jurisdictions!)
 * almost all of continental Europe and Latin America, in elections of legislative assemblies (exceptions: the French Parliament, the Polish and Czech Senates, and a number of countries using FPTP in parallel with PR seats).
 * in English-speaking countries, this includes: the lower houses of Ireland, Northern Ireland (STV), New Zealand, Scotland, Wales (MMP), and the upper houses of Australia.

As the examples below show, using maps of district winners for PR elections has many shortcomings:
 * lack of information provided:
 * in a two-party system, a big *victory for one party is a big loss for the other ; but in a multi-party PR system, it is impossible to tell with a district winner map, areas in which the party came second, from areas where it is completely excluded
 * in PR, district victory is arbitrary: the party coming first may have received as little as 20%, and may be followed by a series of like-minded parties that collectively outweigh the first party in the district
 * meaninglessness:
 * due to Duverger's Law, PR methods tend to increase the number of parties in competition, division being much less detrimental ; but this doesn't mean there can't be pre-declared left-right alliances, which in this case is the meaningful division to show
 * under FPTP, parties tend to be catch-all parties ; under PR, coalitions may be formed after the election and can aggregate catch-all parties with smaller parties appealing to a fraction of the electorate, and sometimes one-issue parties
 * lack of legibility:
 * the number of colors needed in a multi-party system makes maps uneasy to read and of little use

Illustrating the absurdity
Most electoral maps on Wikipedia show district winners even under Proportional Representation, despite it is in such case meaningless, potentially deceptive for election analyses, and illegible overall:

Solution
If one wants to analyze an election under PR, then one should better use party-specific choropleth maps, which use hue progression to show the varying degrees of success in the various districts. The degrees should be divided in 4 or 5 natural breaks (Jenks): this method allows readers to extract the most meaning (unlike arbitrary intervals, or standard deviation) while staying very close to the distribution of data.

I have often seen these maps in use by political pundits, "psephologist"s, and sociologists in continental Europe, in particular France and Germany. The English Wikipedia is largely written by users who do not live in countries using PR, and this probably explains why it hasn't caught up on that particular custom of political science in non-English-speaking countries.

As a sidenote, it could be argued that chorochromatic maps would be more accurate than choropleth ones, especially when a state has districts with largely unpopulated areas, such as the Australian Outback (for upper house elections), the Scandinavian polar circle, the Kazakh Steppe, Russian Siberia etc.

Illustrations
Here's a list of choropleth election maps posted on Wikimedia:

Bulgaria
Excellent map made this year by User:Ivonster04. Uses 5 hues with a rough clustering adapted to each party, that works very well. With maps like this you can understand Bulgarian politics very quickly!

Czechia
Czech Wikipedia User MrGreg has created about a hundred maps, solely for Czech elections (legislative since 1992, presidential runoffs since 2013). He also has two maps of district turnout variations, using 9 hues corresponding to 2.5% intervals [<-10;>10], and two maps of district turnout, using the range of presidential run-off elections.
 * For legislative elections, he always uses the same scale of 8 hues, each corresponding to 5% intervals (range [0-5;35-40]). In some cases he has to manually label districts that are above 40%.
 * For presidential run-off elections, he also uses 8 hues but with a larger interval of 10% (range [<20;>80]).

All in all, they are very legible, and provide immediate insight of each party's strong areas.

Finland
Made by commons:User:Stadscykel in 2011. Used 5% intervals (except for the first 10 percent, and the last interval), which means there were from 7 to 10 hues for the 4 bigger parties. Did not contribute later. PS 2015 was made by commons:User:URunICon.

See also: commons:Maps of Finland - general elections by year and party.

Germany
de:User:Wahlatlas, apparently the owner of the website of the same name, made these wonderful maps, with 5 degrees and (seemingly) natural breaks.

Ireland (Republic of)
Excellent maps were made by User:JandK87 for Ireland's Dail elections (since 1921) and Northern Assembly (since 1973). However, he stopped editing after 2011, came back for the 2016 election, and never edited again. It turns out that another user made and imposed his own maps starting in 2011, where seats won are shown as tiny dots on a dark grey map. see Category:Election maps of the Republic of Ireland on Commons 

Japan
commons:User:沁水湾 made many electoral maps, including one that defines as a choropleth map using 5 hues:

...she even added them on the election page with a switcher!

Kazakhstan
commons:User:ShadZ01 recently produced these awesome maps of the most recent Kazakh elections (2019 and 2021). There are 4 intervals for the minor parties and 5 for the dominant party, which makes sense. The ranges do not seem to be broken with a statistical tool, but rather manually. No legend whatsoever is included; it has to be written somewhere else.

2021 Kazakh legislative election:



Korea (Republic of)
made by commons:User:沁水湾

Nepal
Made by commons:User:Vanished user 1932142 in 2020. Used 6 hues, corresponding to 3-percent-intervals:

Poland
Made by Robert Wielgórski, known by the username Barry Kent (commons) (also wp:pl wp:en) right after the 2007 elections. He made use of varying interval numbers and lengths for each party.

Sweden
Several interesting maps were done by User:Avopeas who was mostly active in 2017, and blanked his talk page in 2019. He is still active on commons (User page) where he updates average polling graphs for Scandinavian countries.
 * (+) we can clearly see the best and worst areas for each party
 * (-) All the maps use the same orange tone.
 * (-) More problematic, the maps use 14 equal intervals and different hues! Impossible to process quickly.
 * (-) the equal intervals are not adapted to each party (ranges are too large for smaller parties, too small for larger ones)

The author did much better with, although the intervals are quite arbitrary.

2014 Swedish general election § Results by municipality

Norway
2017 Norwegian parliamentary election.

Slovakia and others
Australian User:Erinthecute, who has made countless illustration maps for election pages on Wikipedia, recently began to notice the usefulness of choropleth maps, beginning with Slovakia, the city of Graz (see § Cities) and Portugal. She is using 4 to 6 hues by party, usually 5:

South Africa
commons:User:沁水湾 attempted to mix two types of maps, one large with bullet points for seats, the others are small party-specific choropleth maps with number. I am not sure the first one is necessary at all, and removing it would increase the size of choropleth maps, making the numbers legible.

Turkey
Turkish User:Nub Cake made these choropleth maps of the performance of Turkish political parties over the recent years. There are 7 hues, but the margins are not provided:

Ukraine
Made by commons:User:Tohaomg (also uk:Користувач:Tohaomg) following the 2019 snap elections. The number of intervals varies between 5 and 9. The ranges are ad hoc. Excellent to understand where parties are strong and weak. The hues are not, however, standardized (leaving the impression that the 3rd party came in front of the 1st).

commons:User:DemocracyATwork made the same maps twice -- one highlighting regional strongholds (using the shares of the parties' nationwide votes), the other showing regional success (relative to other parties in the region):

User:Green Zero (commons:User:Green Zero) made these maps for the 2014 Ukrainian presidential election:

Scotland
commons:User:Brythones and commons:User:MrPenguin20 made these maps in 2016-2017, using 5% or 2.5% intervals:

United States
Although you would think that the USA, not using Proportional Representation in any circumstance, do not need choropleth maps, commons:User:沁水湾 has found a very good use, with multi-candidate primaries. She uses 5% intervals, which makes extremes very legible:

Multi-colored areas
Mostly used on Wikipedia for the United Kingdom local elections (as each ward has multiple seats)

Various
commons:User:Magog the Ogre/Political maps