8 Apr 2019

Explainer: The Coalition Arithmetic Map

Add up vote-shares, include shifts in vote share because of turnout (or issues), and see what the electoral map looks like.

Go straight to the map.

This is what an election boils down to — constituency wins and losses. This map is the best way we have of exploring past data and playing around to arrive at probable scenarios.

The underlying data set is all party-wise vote share data at the assembly level for the state of Uttar Pradesh from the 2012 and 2017 Assembly Elections and the 2014 General Election.

The political parties are represented by fairly recognisable colors, the gathbandhan with a magenta.

There are three views available (use the menu in the top-left corner to switch between them):


As the name indicates it just shows you who won which constituency. You will also be able to see that while a party may have won a parliamentary constituency, others may have won one or more of the constituent assembly constituencies.


This shows which constituencies changed hands between one election and the next. Select flipped, select the base election and the next election. The dots on the map indicate the party that had the seat, and the constituency color will tell you who captured the seat.


This is the default map and we can promise that this will be the most fun for political junkies. It’s our scenarios calculator where we try to figure out how the Gathbandhan, BJP and Congress will do in 2019.

The first thing you do is pick either the 2014 General Elections, or the 2017 Assembly Election vote shares as the base you work with. We normally pick the 2017 Assembly election.

The first slider lets you figure out whether all of the SPs vote will transfer to the BSP, and theirs to the SP or if some of their combined vote share will drift away to the BJP and the Congress. For example, we can set the vote transfer at 90% with 2% vote share going to the BJP and 8% to the Congress.

The next three sliders allow us to then modify this base vote share to account for change in turnout and voter behaviour. In the bypolls for example, the SP+BSP gathbandhan got 10% more vote share than just the simple sum of their vote share from 2014, and the BJP got 5% less than their 2014 vote share.

In our example scenario, we have the Gathbandhan at +5%, the BJP at -5% and the Congress at +10%

Tell us what you think the likely outcomes are on Twitter  @anthroai

These notes are an experiment in data-driven points of view. We are immersing ourselves in information screens and data patterns and allowing ourselves to connect dots. We emerge to write a note — like the one you’re reading — which is our best understanding at a given moment in time. We believe ourselves to be correct in the moment, but are happy to be proven wrong. In either case we learn and improve.

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Explainer: Polling Booth Vote Share Shift Map