Table 2.

Intervention models for EPA series

Coefficient*/testUnemployedp-valueEmployedp-valueActivep-value
2008 Q4281.1076.79E-06−228.7110.00174.7080.078
2009 Q1738.0852.05E-11−686.8851.06E-0820.6440.711
2009 Q2712.3303.94E-07−788.3083.11E-07−82.6620.114
2009 Q3482.6660.001−665.1946.09E-05−173.1070.001
2009 Q4384.7850.011−534.6200.001−146.0330.009
2010 Q1338.7650.016−420.0680.007−92.2350.031
2010 Q2308.5570.005−328.2150.007
2010 Q3103.3590.091−124.5600.070
ϕ^10.8045.85E-210.8013.41E-200.4470.001
Φ^1−0.1630.111
Φ^2−0.6695.96E-11
Θ^10.5470.0010.5240.001
σ^a78.29287.00760.281
HQ information criterion726.483739.031717.592
DH Test (Normality)0.6270.7314.0920.1294.1200.127
LM Test (ARCH(4))3.3890.4942.7920.5937.8920.095
Q(15)10.8570.62228.2090.00820.4340.059

Notes:

*The entries 2008:4–2010:3 represent impulse-type interventions in the corresponding dates. An impulse is a type of intervention which affects the series at a specific time point and never again. It can be captured by an artificial variable with zeros in all positions except a unit value at the specified date. The corresponding coefficient is an estimate of the difference between the observed and expected values of the series. The error model is an ARIMA(1,1,2) × (0,1,1)4: (1 − ϕ1B) (1 − ϕ1B − ϕ2B2) ∇4yt = (1 − Θ1B4) at

Source: Authors’ own work

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