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Table 5 Regression statistics for ARIMA time series models of area of high-severity fire per year in yellow pine-mixed-conifer forests, fires ≥80 ha, 1984 to 2010.

From: Trends in Wildfire Severity: 1984 to 2010 in the Sierra Nevada, Modoc Plateau, and Southern Cascades, California, USA

 

Last year in model

Model statistic

2010

2009

2008

2007

2006

2005

2004

Parameter estimates

       

Model variance (sigma squared)

0.8409

0.8014

0.8165

0.8117

0.8221

0.8726

1.0163

Intercept

2.2390

2.1572

2.1088

2.1729

2.2357

2.2204

2.2177

Linear trend

0.0450

0.0531

0.0580

0.0508

0.0436

0.0455

0.0501

Autoregressive function (AR) 1

−0.2960

−0.3018

−0.2734

−0.3108

−0.2875

−0.2949

−0.3796

AR 2

0.1720

0.2303

0.2719

0.2857

0.3211

0.3159

 

AR 3

−0.1589

−0.0998

−0.1117

−0.0676

−0.0636

−0.0628

 

AR 4

−0.4137

−0.4334

−0.4715

−0.4652

−0.4556

−0.4443

 

P (linear)

0.008

0.005

0.005

0.018

0.063

0.078

0.083

P (AR 1)

0.151

0.134

0.186

0.143

0.181

0.190

0.096

P (AR 2)

0.424

0.284

0.228

0.206

0.168

0.189

 

P (AR 3)

0.465

0.644

0.609

0.762

0.778

0.787

 

P (AR 4)

0.059

0.043

0.035

0.037

0.043

0.060

 

Statistics of fit

       

Number of observations

27

26

25

24

23

22

21

Number of missing actuals

0

0

0

0

0

0

0

Number of model parameters

6

6

6

6

6

6

3

Mean square error

0.673

0.639

0.649

0.635

0.634

0.661

0.873

Root mean square error

0.820

0.799

0.806

0.797

0.796

0.813

0.934

Mean absolute percent error

24.994

24.125

24.038

23.570

22.365

23.334

30.171

Mean absolute error

0.668

0.654

0.649

0.639

0.612

0.633

0.734

R2

0.338

0.391

0.400

0.402

0.383

0.384

0.221

adjusted R2

0.180

0.239

0.241

0.236

0.202

0.191

0.134

Akaike information criterion

1.305

0.343

1.211

1.114

1.507

2.886

3.137