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.
Accuracy, Cross-national, Forecast, Lead time, Political institutions, Polling, The timeline of elections
949-962
Jennings, William
2ab3f11c-eb7f-44c6-9ef2-3180c1a954f7
Lewis-Beck, Michael S.
dc1269a5-62a3-4bae-bb9b-dd74bebad534
Wlezien, Christopher
e5c172ce-90fc-4bb3-989f-f11e4acb7e53
1 July 2020
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, 36 (3), .
(doi:10.1016/j.ijforecast.2019.12.002).
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
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Accepted/In Press date: 4 December 2019
e-pub ahead of print date: 13 February 2020
Published date: 1 July 2020
Additional Information:
Funding Information:
Earlier versions of this article were presented at the Annual Meetings of the American Political Science Association, Philadelphia, 2016, and San Francisco, 2017. We are grateful for comments we received at those meetings from numerous scholars, including Sabine Carey, Alfred Cuzan, Ruth Dassonneville, Jay DeSart, Andreas Graefe, Randall Jones, Matthew Lebo, Gerald Schneider, and Mary Stegmaier. We also are thankful for the feedback and guidance we received from the editors of the journal and the anonymous reviewers.
Publisher Copyright:
© 2020 International Institute of Forecasters
Keywords:
Accuracy, Cross-national, Forecast, Lead time, Political institutions, Polling, The timeline of elections
Identifiers
Local EPrints ID: 436948
URI: http://eprints.soton.ac.uk/id/eprint/436948
ISSN: 0169-2070
PURE UUID: f8600349-9460-4827-9fc5-b17f26c658ae
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Date deposited: 14 Jan 2020 17:31
Last modified: 17 Mar 2024 05:12
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Author:
Michael S. Lewis-Beck
Author:
Christopher Wlezien
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