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Election forecasting: too far out?

Election forecasting: too far out?
Election forecasting: too far out?
We consider two criteria for evaluating election forecasts: accuracy (precision) and lead (distance from the event), specifically the trade-off between the two in poll-based forecasts. We evaluate how much “lead” still allows prediction of the election outcome. How much further back can we go, supposing we tolerate a little more error? Our analysis offers estimates of the “optimal” lead time for election forecasts, based on a dataset of over 26,000 vote intention polls from 338 elections in 44 countries between 1942 and 2014. We find that optimization of a forecast is possible, and typically occurs two to three months before the election, but can be influenced by the arrangement of political institutions. To demonstrate how our optimization guidelines perform in practice, we consider recent elections in the UK, the US and France.
0169-2070
Jennings, William
2ab3f11c-eb7f-44c6-9ef2-3180c1a954f7
Lewis-Beck, Michael S.
dc1269a5-62a3-4bae-bb9b-dd74bebad534
Wlezien, Christopher
e5c172ce-90fc-4bb3-989f-f11e4acb7e53
Jennings, William
2ab3f11c-eb7f-44c6-9ef2-3180c1a954f7
Lewis-Beck, Michael S.
dc1269a5-62a3-4bae-bb9b-dd74bebad534
Wlezien, Christopher
e5c172ce-90fc-4bb3-989f-f11e4acb7e53

Jennings, William, Lewis-Beck, Michael S. and Wlezien, Christopher (2020) Election forecasting: too far out? International Journal of Forecasting. (doi:10.1016/j.ijforecast.2019.12.002).

Record type: Article

Abstract

We consider two criteria for evaluating election forecasts: accuracy (precision) and lead (distance from the event), specifically the trade-off between the two in poll-based forecasts. We evaluate how much “lead” still allows prediction of the election outcome. How much further back can we go, supposing we tolerate a little more error? Our analysis offers estimates of the “optimal” lead time for election forecasts, based on a dataset of over 26,000 vote intention polls from 338 elections in 44 countries between 1942 and 2014. We find that optimization of a forecast is possible, and typically occurs two to three months before the election, but can be influenced by the arrangement of political institutions. To demonstrate how our optimization guidelines perform in practice, we consider recent elections in the UK, the US and France.

Text
ForecastingLeadTime_IJF_for_publication Final - Accepted Manuscript
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More information

Accepted/In Press date: 4 December 2019
e-pub ahead of print date: 13 February 2020

Identifiers

Local EPrints ID: 436948
URI: http://eprints.soton.ac.uk/id/eprint/436948
ISSN: 0169-2070
PURE UUID: f8600349-9460-4827-9fc5-b17f26c658ae
ORCID for William Jennings: ORCID iD orcid.org/0000-0001-9007-8896

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Date deposited: 14 Jan 2020 17:31
Last modified: 04 Mar 2020 01:32

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