Thematic Mapping – See Data Differently

In the previous post you have seen a parliamentary constituencies map made by my colleague Calum. He did a good job, don’t you think? Today I would like to share with you another parliamentary constituencies map from a different perspective.

Calum’s map prioritises the geography of the UK as we know it. But the geography doesn’t give an accurate depiction of the election results. Scotland and London versus the UK would be excellent examples. This is because of their population densities.

You already know that there are 650 single-member constituencies in the UK and the last voting took place in those constituencies at the UK general election on 7th May 2015.

Of the 650 seats, 533 are in England, 59 in Scotland, 40 in Wales and 18 in Northern Ireland. The electorate of each parliamentary constituency (the collective people of the constituency who are entitled to vote) is on average 71,420. And for that reason some constituencies cover a larger geographic area where people live more spread out in the country – a population density is lower (Scotland). Or a constituency covers a small geographical area where crowds of people live in much smaller space – the population density is high (London).

map, cartogram, UK, thematic

Now look at the Calum’s geographical map again and compare the size of the 59 seats in Scotland with the 533 seats in England – they cover very different proportions on the map. While the Scottish constituencies are mostly larger geographically each constituency in the UK has a similar electorate, as mentioned above on average 71,420.

To give a more accurate depiction of population and support it is better to use a cartogram where the geometry or space of the map is distorted in order to convey the information. In our hexagonal parliamentary results map each constituency is represented by the same size hexagon and a different colour represents the winning party in that constituency. We can label these hexagons with different data, for example MP name and exact electorate.

Zuzana – Cartographic Design Team

For more on election maps and custom parliamentary constituency mapping view our dedicated page here