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Table 4 Various zero-inflated Poisson regression models validated during model selection

From: A spatially-explicit count data regression for modeling the density of forest cockchafer (Melolontha hippocastani) larvae in the Hessian Ried (Germany)

  Model AIC Mixture parameter
g 1(λ i ) = β 01 9.1 7584.1 g 2(ω i ) = β 02; ω i  = 0.52
g 1(λ i ) = β 01 + f 11(DWT i ) 9.2 7262.3 g 2(ω i ) = β 02; ω i  = 0.51
g 1(λ i ) = β 01 + f 11(DWT i ) + f 21(CTH i ) 9.3 7217.5 g 2(ω i ) = β 02; ω i  = 0.50
g 1(λ i ) = β 01 + f 11(DWT i ) + f 21(CTH i ) + f 31(east i , north i ), edf for f 31(east i , north i ) = 28.81 9.4 5708.3 g 2(ω i ) = β 02; ω i  = 0.20
g 1(λ i ) = β 01 + f 11(DWT i ) + f 21(CTH i ) + f 31(east i , north i ),
edf for f 31(east i , north i ) = 117.35
9.5 5092.2 g 2(ω i ) = β 02; ω i  = 0.12
g 1(λ i ) = β 01 + f 11(DWT i ) + f 21(CTH i ) + f 31(east i , north i ), edf for f 31(east i , north i ) = 117.35 9.6 5051.3 g 2(ω i ) = β 02 + f 12(DWT i )
  1. Model complexity increases from model 9.1 to 9.6. The flexibility of the spatial model component increases with increasing estimated degrees of freedom (edf) of the 2-dimensional smoothing function f 3.
  2. with DWT i : simulated distance to water table in October 2007 at plot i (m); CTH i : modeled clay thickness at plot i (%); (east i , north i ): Gauß-Krüger east and north coordinates of plot i defined in relation to the 3rd meridian.