Votes for the 3 parties in Mexico

Commenting on this entry, Matthew Shugart linked to this graph by Rici Lake on votes for the 3 parties in the recent Mexican election. Each dot on the graph represents a polling place:


This is interesting, although I don’t reallly know enough to understand what is meant by comparing polling places. It would be interesting to see graphs at other levels of aggregation also.

Lots more pretty graphs here. The states shouldn’t be ordered alphabetically (I’d prefer increasing order of support for PAN, for example), and I’d like the grid lines to be much lighter (in the individual-state graphs, the grid lines really obscure the dots), but that’s just me being picky. The next step is to do some comparisons to 2000. Are the polling places the same? If so, it’s an interesting graphical challenge because now we have 6 vote proportoins (after scaling to sum to 1 in each election, that’s 4 different outcomes) for each district.

4 thoughts on “Votes for the 3 parties in Mexico

  1. Sounds like 106,000,000 residents desperately need your help!

    If they look hard enough, isn't it a foregone conclusion that they will find something anomalous?

  2. Andrew, thanks for the comments.

    I don't really know how useful these graphs are, either: it was mostly an experiment in using triplots to visualise voting patterns. The Mexican election was interesting because it was an almost perfect three-way contest; I'm still experimenting with visualizations of four-way contests. A barycentric plot of a four-way contest is a tetrahedron, which is a bit harder to reduce to a printed image.

    I regenerated the graphs according to your suggestions. I hope I got the gridlines light enough:

    I'm not sure what other level of aggregation would be useful, but if you have any suggestions let me know. The easy possibilities are by district and by municipality. The districts are (more or less) consistently sized, but the municipalities vary enormously; some are larger than districts.

    I believe the 2000 elections were held with the same sections, but there was a redistribution of districts. Unfortunately, I don't have the 2000 data at the acta level; if you (or anyone) knows where it is available, I'd be happy to try to do the comparisons.

  3. Nice graphs, but you probably should take the geographical information into account as well. Does anybody have a map of the voting districts? Furthermore, are the voting districts of equal size? Weighting the plots might become an issue here.

    Are the data available somewhere?

  4. Martin: I'm not sure what you mean by "taking geographical information into account". What would that imply, other than producing plots by geographical region (i.e. states)?

    Maps of the voting sections are available from IFE ( as PDF maps for each district. (See terminology, below).

    Sections vary in size from 50 to something like 15,000, but sections with more than 750 voters are divided into "casillas", so a casilla cannot have more than 750 voters. The division is done as evenly as possible (i.e. within a section casillas differ in size by at most 1 voter) and with as few casillas as possible. The division is done alphabetically by name.

    The data is provided by casilla, so the variation in size is from 50-750. Only a handful of casillas are less than 200 voters, though. In any event, the graphs are weighted by number of voters: I created them by working out how many voters pertain to each pixel in the plot, and then weighting the darkness of the pixels so that the 99th percentile (of the entire plot) is fully black. If you have a better idea, please let me know.

    The raw data is available at IFE:

    Section maps can be found at:


    A "state" (estado) is like a US State; there are 31 of them plus the Federal District (DF). Each of these elects three senators, and an additional 32 senator are elected by proportional representation.

    For the purposes of the lower house, the states are assigned to five circumscriptions (circuscripciones) and each state is divided into "districts" (distritos) which roughly correspond to US Congressional Districts. There are 60 districts in each circumscription, and they are as equal in size as possible within the constraint that they are each wholly contained in one state. The five circumscriptions are also very close to the same size.

    Each district elects one deputy, and an additional 40 deputies are elected by proportional representation for each circumscription. (So there are a total of 500 deputies.)

    Within each district, there are "sections" (secciones) which are roughly speaking polling places. The detailed maps shows you all of the sections.

    I hope that helps.


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