Dangerous times. Dangerous maps.

A map showing the distribution of people on Trump's foreign banned nationals Executive Order appeared recently.

Map shows location of foreign-born people from 7 banned countries + elected official contact info https://t.co/uOCkECQI9Z #executiveorders pic.twitter.com/TKYzMLeNOI

— Azavea (@azavea) January 31, 2017

You can read the full blog post by the publishers here but here's a screen grab in case the tweet is taken down:

There's a few things that upset me about this map.

Firstly it's non-normalized. It shows totals. Choropleths need a rate or ratio. It was pointed out to me that the map uses Congressional Districts as boundaries and that means the populations are 'roughly' the same so it's all ok.

I'm afraid 'roughly' doesn't cut it. Each Congressional District represents about 711,000 people but you'll notice it's also split by state boundaries so, in fact, it's the data per state that's reapportioned into roughly equally populated areas. That'd be fine for mapping if you discounted Montana, Wyoming, North and South Dakota which encompass one Congressional District each. But they have populations of 1 million, 584,000, 740,000 and 853,000 respectively. None of these population totals can be easily split further without resulting in numbers even further away from 711,000 but it means the map of totals fails to respect these differences. This means the visual message is warped when you're trying to compare across the map. The primary function of the choropleth is to support visual comparison and unless you accommodate the underlying discrepancy in populations it doesn't.

The problem is exacerbated because those States are very large anyway so they inevitably dominate the map. Also, because the map uses the inappropriate Web Mercator projection those northern states are enlarged in relation to the rest of the country too - a further warping that our brains won't adjust for in deciphering the map's message.

There's plenty of other techniques that the map's maker could have used - cartograms, proportional symbols, dot density, hex-binning and so on. Each have benefits and each have drawbacks. The authors said they "wanted to stick with the district boundaries so people could see which district they reside in". So they chose to go with geography so people have less of a barrier to understanding the map. Fine - but the consequence of that decision is you have to be prepared to deal with the inherent cognitive bias and work hard to mitigate it properly.

Even if you think I'm being too nerdy about the issue of totals on choropleths (I'm not) then think about it this way...the map suggests around 3,400 as the bottom value of the highest class in the legend per Congressional District that's a lot of people right? Three and a half thousand of them.  As a percentage? Less than 0.5% and, frankly, that doesn't make the map nearly as persuasive.  Dig a little further:

So the upper class actually goes from 3,400 to 51,652.  And look at how tiny that little place is in downtown Los Angeles. 51,652 people all crammed into Congressional District CA-28 which you can hardly see, compared to 1,620 in North Dakota which you can really, really see. The choropleth doesn't help at all here. A different technique altogether would help. But even at 51,652 that's only 7% of the population. Still not exactly a huge proportion.

The data is also a little misleading. Libya cannot be extracted as a separate country from the American Community Survey used as a source for the map so the 'Other North Africa' designation was used - meaning people not on the banned list are included in the map. How many? Hard to know.

And reds? Hey, this is a sensitive issue. I mean a really f*cking sensitive issue. Red is not the colour to use because it's value-laden. We process it in a particular way and it means 'danger'. If the map is supposed to be an impartial display of the data then red is not the colour to use.

Finally, a friend of mine noted to me that they were concerned that the map even existed given it shows WHERE people on the banned list live. Popups even provide broken down summaries by country.  I countered by suggesting that at Congressional District level there's enough generalization to mask real locations but I take the point and it raises an ethical issue for cartography. In a time of unpresidented [sic] political turmoil, is it morally OK to publish this sort of map just because you can easily scrape the data? What purpose does it support? Given the general outrage that the ban on entry from nationals of 7 countries is tantamount to a partial ban on Muslims then the map could easily incite or inflame the situation further. If the intent is to be impartial then you have to be ridiculously careful to ensure you do just that and this map doesn't. Unless you are setting out to be explicitly persuasive or even propagandist, cartographers and map-makers have a responsibility to make maps that are not misleading and when dealing with sensitive subject matter it becomes crucial.

I am absolutely sure that the map-makers here actually had the opposite intention because they include contact details for Congressional Representatives - presumably as a call to action to encourage people to call in their opposition to the ban. Trouble is, for every one that might go to that effort there will be many more that look at a sea of red and interpret it differently. That's the power of maps.

As it stands the map is dangerous. It shows where people live that are currently on a banned list and that serves no purpose. It uses a good technique but poorly which is nothing more than creating visual alternative facts. It uses the wrong projection which exacerbates the problem. It uses slightly dubious data and, certainly, a bad choice of colours. I'd ban this sort of mapping. Period.

Favourite maps from 2016

2016 hasn't been the best year. Tinged with the sadness of so many iconic people checking out before having to face the political turmoil ahead, the number of 'best maps of the year' blogs has also diminished. Greg Miller has already posted his Best Maps of 2016 on the National Geographic blog and we share quite a few in common. Is that consensus? Or possibly the cream of the crop are that much more distinct from the rest? What of others? Is blogging really dead because no-one wants to read anything beyond 140 characters any more? I'll just put these here to log my personal favourites from the year.

I wrote last year that I felt the quality of cartography was improving and I see a shift in the balance in quantity of poor maps vs good maps. I think the pace of that shift may have slowed a little but it's still on course. As people's recognition of weak maps becomes more atuned; and their tolerance for meager offerings becomes lessened, it's harder to throw something into the ether and make it stick. That translates to the map-making process where greater care is taken not only in the analysis and accuracy of the data but also the artistic representation. Whether digital or hand drawn, there's certainly more aesthetically pleasing maps being made.

So, in no particular order here's some of my favourites:

The Two Americas by Tim Wallace at New York Times

The Presidential election brought out numerous thematic maps but Tim Wallace stole the show by transforming the electoral geographies into two pseudo imaginary landscapes complete with new labels. They're really just red and blue maps, one for Trump and one for Clinton, each showing the territory of the two candidate's winning counties but it shows how a cartographic imagination can transform a map into something completely new.

Shan Shui in the World by Shi Weili

A traditional shanshui Japanese painting produced computationally. A beautiful piece of work that demonstrates how cartographies of the past can be re-imagined using modern workflows to go beyond what we think is possible. It's based on building height data for Manhattan Island. Stick it on the wall....that's all!

Modern London in the style of John Rocque's 1746 map by Mike Hall

I continue to be impressed by the work of Mike Hall. This is a work in progress for a private client but shows how working in only two-colours can be so sweet! Mike has also done some great single colour retro maps this year which are also worth a mention,

The North American Continent by Anton Thomas

It's not even finished yet but this is a stunning large format hand drawn pictorial map. The detail is exquisite. It's painstaking work but the result is pure cartographic gold. I love the way Anton drew in the labels first then fitted the detail in around those key items - the reverse of how many make maps.

Transportation Clusters by Martin Grandjean

A force-directed layout of the airline transport infrastructure. If the geography doesn't work to display the data, make the data work to display the geography. It makes much more sense to escape the grip of real geographies for so many datasets and this example works well. The colours and layout add to the overall composition.

Attention all Shipping by Jane Tomlinson

How do you make the BBC shipping forecast visually interesting? Paint it! The British obsession with weather is encapsulated with the daily shipping forecast and the strangely named areas at sea which it references. Tomlinson refers to it as visual poetry which may even be a new form of cartographic sub-genre. Either way, a beautiful map of an otherwise mundane subject.

Hiking in the Grand Canyon by Charles Preppernau at National Geographic

Scrolly story maps have become popular this year. This example is perhaps the pinnacle of the genre, skillfully merging fantastic photography, video, text and other multimedia components with superb cartography. But it doesn't end there. The maps are windows and they're used creatively with transitions, pans, zooms and fades that bring focus. The changing of the map's base to show winter snowfall is genius.

Paths of Amity by Andrew DeGraff

I'm not even sure Andrew drew this one in 2016 but I came across his work in 2016 and it's stunning. His movie maps series plots the paths of the key actors and story for different films. I picked his Jaws map here but, equally his maps of Star Wars and others are just as good. He builds the film's locations as a single uninterrupted backdrop then plots colour-coded lines throughout the map. Simple idea, beautifully drawn. More here.

Here There be Robots by Eleanor Lutz

There were several maps of Mars in 2016 but, for me, this hand drawn map was the best. It has an antique quality with clever use of colour and, in particular, the relief depiction. Colours change as the relief changes at key contour lines which makes it appear a little like a carved woodcut. The various adornments such as the measured graticule, rhumb lines and hand-written style fonts add to the effect.

National maps for Switzerland by Swisstopo

The national maps of Switzerland have always been at the pinnacle of national map agency cartography. Swisstopo have updated their topographic map series and they've somehow managed to improved on them. Clarity, composition, colour, typography and beautiful landform representation work in perfect harmony at each scale and acrsoss the scales. There's a splash more colour and a little more sans serif but they're unmistakably Swiss.

FaVVEs by Roger Beecham et al.

Small multiples are a great way to juxtapose different aspects of a related dataset. Here, the idea has been developed to show faceted views - multiple perspective small multiples that allow more than one variable to be viewed concurrently. Symbol and cognitive overload are often the cartographic enemy but this research shows that it is possible to develop new ways of seeing that make sense, work well and look good!

The Peaks and Valleys of Trump and Clinton's support by Washington Post

There weren't any valleys as promised in the map's title but the one thing I liked about this map was how they rotated the map so east to west was top to bottom. It works better that way on a scrolly story map layout. A neat way to modify how the map is presented given the form it is likely to be viewed in.

Five+Years of Drought by John Nelson

A bivariate map showing the relationship between severity of drought conditions and length of sustained drought using bold but stunning colour choices. All of the context to the map sits (nearly) on one subdued visual plane with text, linework and labels almost apologetically fading away to create contrast with the main theme and force you towards it. Clever symbology and subtle topography.

Mapping the Shadows of New York City by Quoctrung Bui et al. at New York Times

Simple idea. Beautifully executed. But this isn't just a computational exercise - it's an interactive map that gives you a tool tip showing the amount of day in shadow for different seasons as you pan across the map. Monochrome backdrop and good use of a single colour for the shadow detail which differs by season.

There's plenty of other great maps I could have included but then it becomes a comprehensive list rather than my personal highlights.

Finally - let's have a brief roll call for some of the carto crap out there...The stuff that would make you laugh if it didn't make you cry. There really is far too much to mention but here are some delightful examples presented as small as I can to avoid personal injury:

My eyes...my eyes...

Because no-one fact-checks any more anyway...

And sometimes you don't even know what the map is even trying to show (it's the election!!!)...

Generalisation is a core cartographic technique but you can go a bit far (with only 931 responses)...

And there's also problems when you zoom out a little too far...

Rainbow hurricanes...

Extreme heat - the obligatory annual entry from the meteorological community...

That's it. Happy New Year!!!

Can't see the wood for the trees

The Mayor of London's office recently published the London Tree Map. Like other similar maps of major cities (e.g. New York, Melbourne) it 'suggests' by its very existence that it's a map of every tree on the streets of the city.

(Click to open the actual map in a new window)

The map looks decent enough and I was compelled to head to the London Datastore to take a look at the data myself to see if there was value in playing with it.

The main map page is clear to say the map is 'an initial attempt' to present the tree data but when you dig into the small print, in fact there exists a number of issues including:

• incomplete coverage from different Boroughs
• surveyed dates are unknown and likely prior to the date specified
• no agreed or consistent framework for the data collected
• lack of naming conventions for recording species

The data represents an uncoordinated set of efforts to collect information. I'm fine with that; and also that they are highlighting these drawbacks. But, how many people are going to go beyond the map and dig into the veracity of the data? As with most (all?) maps, this one lies but this one tells huge porkies! With an estimated 8 million trees in London, this is likely only 10% and the data is so fraught with possible error it makes even this 10% questionable.

Publicising such a map leads to misinformation. It's duplicitous by the very act of it being published though I am in no way suggesting those behind it did so intentionally.

A couple of the geo-twitterati thought I was being overly harsh, suggesting "it's a good start", "it's better than no map at all", "it's just an attempt", and "I've seen worse", I don't disagree with these sentiments (and yes, there are way worse maps on the interwebs) but these sort of comments gloss over my general point. Whatever you put on the internet becomes THE view of reality regardless of the quality of the data. In this sense, this map becomes THE view of the pattern of trees in London. There's no getting away from that reality and it does the subject matter a disservice in my opinion.

My suggestion is simple. If you have access to data like this, be careful and seriously consider not mapping it until you've dealt with the errors and inconsistencies. I appreciate that one of the first acts when you have data is to stick it on a map but sometimes restraint is the better path.

All of the same points about raising awareness and issuing a call to action for a framework for consistent and thorough data collection can be made without making a map that lies so badly. At least the unsuspecting public won't get fooled quite so much,

The NYT election map

It's election time in the US. It has been for well over a year (which is madness in itself) but we're down to the wire now with only a week to go before polling in what must be one of the most hate-fueled, vitriolic contests ever. Lies and misinformation have taken centre-stage but the sad truth is there are people (people who vote) who are easily taken in by lies and misinformation. They are sold it as a version of the 'truth' they can relate to and in which they wholeheartedly believe. And so that's how propaganda becomes reality and how candidates gain disciples. It's often the same with maps because they too sell a version of the truth.

We're arguably on the cusp of something far more important than worrying about a map in a newspaper but to my mind, at least, today's HUGE map in the New York Times warrants some cartonerd attention.

In today's print NYT: the most detailed election map we've ever printed: 30,000+ zip codes across a 4-page spread. pic.twitter.com/yjUHNSEvU2

— NYT Graphics (@nytgraphics) November 1, 2016

It is a truly magnificent piece of work. Large format. Eye-catching. Detailed. The US is a big country so if you want to show 30,000+ zip codes you better make your map big. I am a huge admirer of the New York Times graphics team and their cartographic work but this map, I'm afraid, contributes to the misinformation that has become so toxic this election season. Let's not worry about the periphery because it's the main map that takes centre-stage. It's that image which is defining and the impression that people see.

So what do they see? RED...lots of red. Any map that attempts to summarise a sparsely populated data set into a surface that exhausts space will mislead. It's inevitable. And with the USA, with a very heterogenous population distribution and vast swathes of land with barely a single rattlesnake of voting age it's a problem that is accentuated. The map uses Zip Code Tabulation Areas instead of counties, voting precincts or other geographies. There are problems with how ZCTAs mis-shapes the view but, frankly, any arbitrary boundaries have the same problems - the Modifiable Areal Unit Problem - statistical (and ultimately visual) bias that results with how you aggregate data into areas. The geography is what it is...but rather than perpetuate visually incongruous issues it's beholden on map-makers to deal with it.

For the last few years in my day job I've given a workshop at the Esri International User Conference that takes a single dataset of the 2012 election results and explores a range of about 20 different ways to present the very same data - each of which tells a very different story. Some of the maps can clearly be used to portray a particular dimension of the result and some can be used in deplorable ways (pun intended). Some reveal detail. Some mask it. Some show red. Some blue. You can see the full range of maps here if you're interested. The point of the session is to open people's eyes to the inherent biases that maps contain. What surprises me year on year is that an audience of people heavily invested in geo are equally surprised at the problems we explore. I guess it's to be expected - not every geo-expert is going to be a cartographic expert and they come to the session to learn and that's a great thing. But they are merely a small fraction of the population. The vast majority have no access to this sort of education. More than that - they have no idea they might even benefit from it or that there's a problem with how they read the maps they are served.

It's really a much bigger problem of geographical illiteracy and the lack of the basic need to view maps and graphics critically. With all these much larger issues it therefore becomes crucial for media organisations and those involved in communicating information to be cognisant of the limitations of the consumer. It's not really their fault - we're all born that way and we have a natural tendency to believe what we see, especially if it comes from a so-called reputable, impartial source. Maps should portray reality in a way that deals with the biases people inevitably see - to counter them rather than feed them. You only have to read the comments in reply to the NYT tweet to see how the map has been viewed and interpreted.

The problem with this New York Times map is the country itself which, admittedly, there isn't much they can do about but they could deal with the problem using different maps.  The size of the areas used to summarise the data are unequal. Some are therefore more visually prominent than others. Republicans hold on to large swathes of centrally located territory. Democrats get a shed-load of votes from the smaller, peripheral northeast. Additionally, they contain very different numbers of people so population density is unequal across the map - yet in terms of the symbology, each area is treated the same.

So you end up with large swathes of sparsely populated large areas in the mid-west being seen prominently and very small, densely populated areas on the coasts being seen much less prominently. The problem is compounded by two other factors - colour and focus. Red for republican is a colour that is seen more brightly than blue for Democrat. It is cognitively processed as 'more important'. Our eyes also naturally tend towards the centre of an image and a map on first inspection - so that's our initial focus. this all adds up to one massively misleading picture of the political geography of the USA. It screams REPUBLICAN which given Trump's persistent comments about the corrupt media is either an attempt for NYT to redress the balance or the Russians are to blame. And yellow for the marginal areas? I understand the desire for a neutral colour but in a generally two-horse race (mule, elephant, whatever) adding in other colours paints a different picture as well.

It can be different as these following maps of the 2012 election results, mapped by county, show. Using a value-by-alpha approach that overlays a layer of population density that is symbolised so that sparsely populated areas are more opaque will modify the image. It tunes out sparsely populated areas and brings a little focus to the areas with more people (more voters). All that deep red on the NYT version has now gone. Focus is shifted.

A cartogram does a similar job but by changing the shape of the areas - either warping them in relation to population density (e.g. a population equalising cartogram) or by giving each unit area the same shape (e.g. a hexagon grid). Yes, these are abstract and there's sometimes a challenge understanding the geography but they deal with the problems.

There's even the simple, yet effective, proportional symbol map that often gets overlooked. Symbol overlaps are often hard to reconcile but the symbol sizes do a good job of showing where there is more and where there is less as well as encoding the different colours.

Finally in this small selection of the myriad of alternatives, a dasymetric technique which uses a secondary layer of data into which you can reapportion the data can also show a more accurate distribution of information (e.g. dasymetric dot density) though, of course, any map of population data presented in this way will take on a similar appearance because, well, that's where people live!

Ultimately, there are dozens of different ways that the map can be made. None are 'right' and none are 'wrong' but they all tell different versions of the truth. This isn't cartographic pedantry. It's an important issue because it plays to people's views, opinions and search for the truth. My point here, is that maps can be extremely dangerous graphic tools. The NYT have, in my opinion, contributed to the misinformation that has enveloped this election by publishing this map in the form they chose. It presents a version of the truth that suits a particular view of reality. It is biased and dangerous. It's also too late because it's out there now and is simply just another piece of rhetoric people can use to support their own version of the facts.

By the way, I don't get to vote in the US election but I have lived and worked in the US for 5 years and call it home. Please...do yourselves a favour and go vote. You only have to look at what happened in the UK a few months ago where the vote was to leave Europe...a vote massively impacted because many people failed to turn out to vote who would otherwise have voted not to leave. You can't vote by liking or re-tweeting. Whatever the map says to you...just go and vote and help redraw the one you want.

UPDATE: Since writing this less than an hour ago the Washington Post has published a very well-timed piece entitled Election maps are telling you big lies about small things. They've been advocating cartograms based on one area per electoral college vote which I like. It retains a State-based appearance (which isn't as difficult to read as the population equalising versions) while doing a good job of presenting a visually balanced view of the data. I encourage you to read.

UPDATE 2: And now a good review of past approaches from NYT here. A rebuttal of the criticism they've faced? Maybe. They try and frame the big map as an attempt to look at the way physical geography impacts political patterns. That's a very nuanced way to explore the distribution of voting and I'd still argue that most who read the map will take away one message...more red = more Republican. Seven days out from the election is not the time to be playing with people's inherent perceptual and cognitive bias.