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

Fire Ecology

Table 3 Regression statistics for ARIMA time series modeling of percent of high-severity fire per year for yellow pine-mixed conifer forests, for fires ≥80 ha 1984 to 2010.

	Last year in model
Model statistic	2010	2009	2008	2007	2006	2005	2004
Parameter estimates
Model variance (sigma squared)	0.0079	0.0080	0.0082	0.0083	0.0087	0.0086	0.0092
Intercept	0.3018	0.2996	0.3014	0.3038	0.3060	0.3024	0.3030
Linear trend	0.0027	0.0030	0.0028	0.0025	0.0023	0.0027	0.0026
Autoregressive function (AR) 1	−0.9501	−0.9185	−0.9380	−0.9674	−0.9373	−0.9526	−0.9509
AR 2	−0.7800	−0.7314	−0.7777	−0.7702	−0.7352	−0.7505	−0.7429
AR 3	−0.6472	−0.5725	−0.5748	−0.5695	−0.5489	−0.5933	−0.5933
AR 4	−0.5099	−0.4937	−0.4812	−0.4897	−0.4648	−0.4707	−0.4718
P (linear)	<0.001	<0.001	0.002	0.008	0.031	0.017	0.036
P (AR 1)	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001	<0.001
P (AR 2)	0.006	0.011	<0.001	0.011	0.019	0.017	0.022
P (AR 3)	0.014	0.038	0.041	0.045	0.060	0.044	0.052
P (AR 4)	0.016	0.021	0.026	0.025	0.041	0.038	0.046
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	6
Mean square error	0.007	0.007	0.007	0.007	0.007	0.007	0.007
Root mean square error	0.081	0.081	0.082	0.082	0.083	0.082	0.084
Mean absolute percent error	20.124	19.560	19.703	19.825	20.263	18.924	19.640
Mean absolute error	0.066	0.065	0.066	0.067	0.068	0.064	0.066
R²	0.561	0.561	0.566	0.582	0.540	0.560	0.561
adjusted R²	0.456	0.452	0.452	0.465	0.405	0.423	0.415
Akaike information criterion	−123.514	−118.436	−113.120	−108.025	−102.520	−97.849	−91.927