We’ve been evaluating the various merits of key dashboarding applications including Tableau, Power BI and Excel, based on their mapping capabilities. We quickly decided that Tableau would provide the best solution, because:
- It is possible to overlay point-based maps on top of thematic (filled) maps
- The software can cope easily with millions of data points
- If you know which workarounds to apply, it is possible to produce thematic maps at postal sector level, with postcode-level detail for point-based maps
- The look, feel and functionality of Tableau’s dashboards currently have the edge over other applications
It is widely-known that Tableau’s built-in mapping capabilities leave a lot to be desired if you’re working on anything specific to the UK: the best level of detail you can expect is postal district level (e.g. GL7 would be the postal district level of postcode GL7 2NH, and for reference, there are almost 1.8 million postcodes in the UK, but only around 3,000 postal districts).
This is not very useful if you’re trying to plot a postal sector thematic map or postcode-accurate locations of supporters or customers.
So how do we get around this?
The solution for plotting the point-based maps is relatively straight-forward, and one that I believe is fairly well-known: you have to append latitude and longitude to each postcode and use those fields instead of Tableau’s own generated latitude and longitude fields.
The solution for plotting postal-sector thematic maps is slightly more complicated, and harder to find. Trawling the message boards does not reveal an acceptable solution – it was only after watching one of Tableau’s online training videos that we found what we were looking for (buried at 3mins 22secs in their video on Polygon Maps). Come on Tableau – you should be shouting this from the rooftops!
It involves connecting to TableauMapping.bi via Tableau’s wdc (web data connector) facility. TableauMapping.bi is a fantastic website that provides free-to-use mapping datasets for the whole of Europe and several specific countries. In our case, we only needed their UK Postal Sector and Postal District polygon maps, but it opens up a whole range of possibilities for providing mapping solutions for our international clients.
Once the thematic/point-based map view has been created, you can use a combination of
- filters to allow the user to select which catchment area to view
- parameters to enable the user to select which customer/supporter group or geodemographic profiling data to focus on
- navigation buttons to switch between postal sector vs postal district level views
So at the touch of a button, both the maps and the accompanying charts and statistics update almost instantly.