Predicting bloc support in Irish general elections 1951–2020: A political history model

Figures & data

Table 1. Political History Model: Seemingly unrelated regression models explaining vote share of Fianna Fáil, Fine Gael, Independents, and the Left bloc as a function of government incumbency, short-term popular support, and shocks in Irish elections 1951–2020.

	Fianna Fáil	Fine Gael	Indep.	Left
In Government	−1.288^+	−3.792**	−4.881**	−3.584***
	(0.676)	(1.405)	(1.735)	(1.014)
Short-Term Popular Support	−0.529***	0.401*	0.591***	0.434**
	(0.127)	(0.160)	(0.145)	(0.159)
Shocks
FF coalitionable	−7.860***	−5.966**	2.136**	4.454**
	(0.988)	(1.867)	(0.805)	(1.401)
Global Financial Crisis (GFC)	−26.061***	3.288	3.988**	10.473***
	(1.683)	(2.392)	(1.391)	(2.017)
Constant	69.875***	21.326***	−0.251	9.993***
	(5.372)	(5.086)	(1.145)	(2.673)
Model performance, average prediction error & within-sample diagnostics
R^2	0.981	0.646	0.860	0.919
Root Mean Squared Error (RMSE)	1.220	3.030	1.387	2.173
x̄ MAE	0.891	2.475	1.144	1.661
x̄ Median AE	0.584	2.086	1.005	1.520
Largest Absolute Forecast Error	3.492	5.530	2.770	5.017
Out-of-sample diagnostics
Jackknife
x̄ MAE	0.914	2.520	1.158	1.684
x̄ Median AE	0.894	2.492	1.150	1.671
Largest x̄ MAE	1.061	2.737	1.298	1.823
Absolute Forecast Error <1.1-point	55%	20%	45%	40%
Absolute Forecast Error 1.1-3.0-point	40%	35%	50%	30%
Absolute Forecast Error 3.1-5.0-point	5%	15%	5%	15%
Absolute Forecast Error >5.1-points	0%	30%	0%	15%
Two observation omission
x̄ MAE First-Two-Obs.-Deletion	0.920	2.584	1.161	1.696
1951 election Absolute Forecast Error	1.689	2.875	2.898	1.231
x̄ MAE Last-Two-Obs.-Deletion	1.215	2.744	1.280	1.584
2020 election Absolute Forecast Error	2.922	3.539	3.563	6.837
One-Step-Ahead
x̄ MAE	5.777	3.034	1.671	3.241
x̄ Median AE	1.286	2.500	1.162	1.607
Largest x̄; MAE	8.541	3.482	2.094	4.758
Absolute Forecast Error <1.1-point	42%	0%	33%	17%
Absolute Forecast Error 1.1-3.0-point	33%	17%	42%	33%
Absolute Forecast Error 3.1-5.0-point	8%	25%	25%	17%
Absolute Forecast Error >5.1-points	17%	58%	0%	33%
N	20	20	20	20
Log-likelihood/AIC/BIC	−155.1017/350.2034/370.118

Note: Entries are unstandardized coefficients of seemingly unrelated regression with standard errors in parentheses; *p < 0.05; **p < 0.01; ***p < 0.001. Out-of-sample one-step-ahead approach calculated on elections from 1981 onwards.

Figure 1. Out-of-sample forecasts of Fianna Fáil vote share (diamonds) using a jackknife approach compared with official results of 20 Irish general elections 1951–2020 (circles) with vertical bars from diamonds representing 95% confidence intervals associated with estimates. Note: Grey bars are the absolute error between the forecast and official result.