Voting patterns in the United States

Because of my interest in social statistics, I’ve been exploring county-level results from the US 2016 presidential election. The map below (click to zoom) summarises the results (blue for Democrat and red for Republican, coloured according to how strongly counties voted one way or the other). Nine of the more extreme counties are highlighted.

Most of the variance in this data can be explained by demographic factors such as race, age, education levels, local unemployment, rural-urban continuum code, and median household income. The latter is particularly interesting, and the chart below provides a summary.

On a scale from −0.5 being 100% Republican to +0.5 being 100% Democrat, the curve shows the average vote of counties by 2016 median household income (where the averages are weighted by county population sizes, and LOESS smoothing is used to draw the curve). Overlaid on the diagram is a bar chart for the total population of different median household income groups (the scale for this bar chart is on the right).

It can be seen that, at the very poorest end, votes are balanced between Democrat and Republican. For example, here are the 7 poorest counties in the United States, by median household income. They are all rural:

Above that bottom end, votes trend Republican, with the peak Republican vote occurring at median household incomes around $40,000. Above about $56,000, counties swing Democrat, and the Democrat vote increases with increasing wealth. For example, here are the 4 richest counties in the United States, by median household income. They are all part of the Baltimore–Washington metropolitan area:

Essentially, the Republican Party seems to have become the party of the poor, particularly the rural poor. Indeed, the (population-weighted) median of 2016 median household incomes for Democrat-majority counties was $61,042; while for Republican-majority counties it was $52,490 ($8,552 less). For a visual perspective, the map below limits the previous one to counties with a 2016 median household income below $56,000. It is precisely because the Republican Party has become the party of the rural poor that these maps are mostly red. I had not fully appreciated this before analysing the data (although others have), but it certainly explains much of recent politics in the US. However, predicting the results of the next presidential election would require some solid demographically linked polling data as well as a good voter turnout model.


Hello again, little tree-kangaroo

The Wondiwoi tree-kangaroo (detail of an illustration by Peter Schouten)

National Geographic recently reported an interesting story about the Wondiwoi tree-kangaroo (Dendrolagus mayri). Until recently, this arboreal marsupial was known only from a single specimen collected in the Wondiwoi Peninsula of West Papua in 1928. It was thought to be extinct, and was listed on the “25 most wanted lost species” at But when an amateur expedition visited the dense mountain forests of the Wondiwoi Peninsula, there it was, living happily in the trees. A good-news story from the animal kingdom, for once.

Surprised to find kangaroos living in trees? There are a number of related species that do this, in the rainforests of New Guinea and northern Australia. In fact, members of the kangaroo family live in a range of different habitats (the rock-wallaby would be a less dramatic example).

A Belgian solar car climbs the mountains of Chile

Punch at CSA 2018 (picture credit)

Well, Punch Powertrain Solar Team, from Belgium (above) is currently racing against just one other Challenger car in the Carrera Solar Atacama in Chile (see: and the live tracker). I thought it would be interesting to compare Punch’s performance against that other mountain race, the 2018 American Solar Challenge, won by Western Sydney University.

The two races can’t be compared directly, however. The Carrera Solar Atacama has a greater elevation range (sea level to 3415 m, compared to 296 m to 2585 m for this year’s ASC). The CSA is south–north, rather than east–west, and takes place around 20° closer to the equator, on average. More dramatically, however, this year’s ASC allowed 2 m2 supplementary solar panels during static charging (see image below). This made the ASC a faster race.

WSU using supplementary solar panels at ASC 2018 (picture credit)

What I have done instead is compare the average speed for each segment against the approximate average climb rate, using the information provided in Punch’s wonderful infographics (see their social media: ). The corresponding datapoints for WSU were calculated in exactly the same way, and linear regression was applied for each team (see lines on the chart at the bottom of this post). The flatter line for Punch shows that they were less affected by the steep climbs. This is presumably due to their fancy new motor, which has a half-speed/double-torque mode. This Mitsuba motor was built by Nomura Co to Punch’s requirements.

Punch’s motor, built by Nomura Co (picture credit)

Update: the chart below has been updated with new data.

Powers of 10: the Australian version

In the footsteps of the classic short film, we explore the powers of 10 (click to zoom).

We begin with a classic NASA photograph of the Earth seen from Saturn, with a field of view (in the distance) about 100,000,000 km across. We zoom in by a factor of 10 to see the Earth and the Moon beside it. After three more such jumps (to 10,000 km), the Earth fills the frame. Three further jumps (to 10 km) zooms in on Melbourne, Australia. Two more jumps show us the city centre (1 km) and St Paul’s Cathedral (100 m). Another two jumps (to 1 m) give us a small boy on the grass beside the Cathedral. Two more give us the iris and pupil of his eye (1 cm) and a small patch of his retina (1 mm). Finally (at 100 µm or 0.1 mm), we see red blood cells inside a blood vessel in his retina. Fifteen jumps in all, zooming in by 1015.

Sea levels in the Pacific

I recently visited Port Vila, capital of the Pacific island nation of Vanuatu (the photo above is from the Port Vila waterfront). Port Vila is the site of a sea-level measuring station. It is interesting that, although local newspapers are deeply concerned about sea level rise, the average sea level rise between 1993 and 2017 at Port Vila was essentially zero (see chart below, which uses LOESS smoothing of monthly measurements).

How can this be? Aren’t global sea levels rising at 2–3 mm per year? Well, “global sea level” is a rather theoretical concept. Ocean temperatures are not uniform. Some islands are rising out of the ocean. Others are sinking. Air pressure, and the El Niño Southern Oscillation cycle, have a huge effect on sea levels too. As they say, it’s complicated.

The NASA map below shows that some areas of the Pacific have actually seen a long-term reduction in sea level (independent of any upward or downward movement of land). Other areas, of course, have seen quite rapid increases (the increases and decreases average out to a rise of about 3 mm per year). The map covers data only up to 2008, however. Since 2008 was roughly the peak for the Port Vila data, it doesn’t quite explain the last decade of the graph above. If I had to guess, I’d assume that some of those sea-level-decrease areas on the map had shifted a bit.

New solar car teams #5: Appalachian State

It’s a bit of a stretch calling Appalachian State University / Sunergy  (click: ) a new solar car team. Having rebuilt the shell of an old car donated by PrISUm, they first hit the American solar car scene at FSGP 2015 (where they failed scrutineering), ASC 2016 (where they came 6th), and FSGP 2017 (where they came a satisfying 2nd). But this year they did become a new team (in the Cruiser class), with their first car built from scratch, ROSE.

AppState’s ROSE (picture credit)

The Cruiser class is, in some ways, a tougher race than the Challenger class, but it’s an easier sell (to sponsors and to the general public). For example, I’m a big fan of Nuon’s beautiful and efficient Nuna 9S (the Stradivarius of solar cars), but you can’t really point to it and say “this is the future of transportation.” It’s far too cramped for that – more like an elegant mathematical proof or a work of art than like a practical vehicle. However, “the future of transportation” would be a feasible label for Cruisers like Eindhoven’s Stella Lux or Bochum’s SunRiser – so it’s not surprising that many solar car teams want to emulate those two pioneers.

The Stradivarius of solar cars, from Dutch champions Nuon, is nevertheless a little cramped (picture credit)

AppState did the right thing by attending ASC 2018, although their car had apparently not even been turned on before the race. Because of electrical problems, they did not manage to drive the entire distance – but they obtained good experience, and they know what to fix now. We can expect to see a greatly improved version of their car at the 2019 Bridgestone World Solar Challenge. Good luck, y’all!

AppState’s multi-stage path to the BWSC is a good model for other intending Cruiser class teams to follow. And with a drag coefficient of 0.17, they have not made the mistake of neglecting aerodynamics – because, in the Cruiser class, efficiency still rules.