Which candidates outperformed their party in the 2016 Welsh election?

As we wait for votes to be counted in the 2021 Senedd election, it's likely that we will know the constituency results several hours before we know how things will play out on the list.

One thing to bear in mind is that votes for candidates in a constituency do no always translate into the same level of support for that candidate’s party on the list. This is because of split-ticket voting, where voters cast votes for two different parties across the constituency and list ballots.

Figure 1: % of voters casting split tickets in previous Welsh election

This is a pretty common occurrence (see Figure 1). The choice to split your ticket can be driven by a number of different reasons, from tactical voting, to a personal vote for a specific candidate, to voting for a party on the list that doesn’t stand on the constituency ballot — not to mention potential confusion over the voting system.

With this in mind, the graph below lets us look at which candidates outperformed their parties in 2016. This basically the difference between the share of votes for a constituency candidate and the share of votes for that candidate’s party on the list in that constituency.

If a point is below the diagonal line, this means the candidate did better than their party. Above the line is the opposite.