Vote Intention Poll Performance: Irish General Election 2020

How did the pre-election polls for the 2020 Dáil perform?

On Saturday 8th February, Irish voters cast their votes.

How well did the pre-election polls do? This article discusses their performance.

Final Polls

Six companies conducted vote intention polls during the Irish General Election campaign. The latest date that the survey fieldwork stopped was 2nd February — six days before the election.

According to RTÉ, Sinn Féin received the highest share of first preferences: at 24.5%. Fianna Fáil were second on those preferences, at 22.2%. Fine Gael were third, with a share of 20.9%.

The first counts determined the share of first preferences. (Image: RTÉ)

In order to measure accuracy, we are interested in:

  • SF Lead: the difference of Sinn Féin and Fianna Fáil vote intention share estimates minus the actual Sinn Féin lead in Ireland.
  • Three-party mean absolute error: the average of the absolute difference between vote intention estimates and the actual vote share, for Fine Gael, Fianna Fáil and Sinn Féin.
  • Five-party mean absolute error: a similar calculation, but extended to Labour and the Green Party.

The table only shows the last poll from each company. Behaviour and Attitudes are not shown. Their final poll was conducted about a month before the election.

Of the final five polls:

  • Two companies (Survation, and Ipsos MRBI) all estimated Sinn Féin’s first preference lead within one point.
  • Three companies (the two above plus Red C) all had a three-party mean absolute error below two points.
  • Four companies (that list plus Panelbase) had a five-party mean absolute error below three points.

After the election was announced, polling series identified a large increase in preferences for Sinn Féin. This highlights the importance for accuracy of conducting polls close to the electoral event.

SF support has reached a high point. (Image: Red C)

Polls offer an imperfect, but valuable, view. Sinn Féin topping first preferences was visible within the dusty mirror of survey research.

Improving the access to data tables would be a trustworthy move. The Google Sheet web page containing the calculations is available to view)

This blog looks at the use of statistics in Britain and beyond. It is written by RSS Statistical Ambassador and Chartered Statistician @anthonybmasters.

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