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Check poisson-link delta models #186
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These are now robust and match VAST exactly (local tests for future reference). We should probably add a vignette because the connection between the linear predictors and inverse-linked predictors is unique. At the very least, these need more explanation in the model description vignette. library(sdmTMB)
fit <- sdmTMB(
density ~ 1,
data = pcod,
mesh = make_mesh(pcod, c("X", "Y"), cutoff = 10),
family = delta_poisson_link_gamma(),
)
summary(fit)
#> Spatial model fit by ML ['sdmTMB']
#> Formula: density ~ 1
#> Mesh: make_mesh(pcod, c("X", "Y"), cutoff = 10) (isotropic covariance)
#> Data: pcod
#> Family: delta_poisson_link_gamma(link1 = 'log', link2 = 'log')
#>
#> Delta/hurdle model 1: -----------------------------------
#> Family: binomial(link = 'log')
#> coef.est coef.se
#> (Intercept) -0.6 0.29
#>
#> Matérn range: 32.44
#> Spatial SD: 1.48
#>
#> Delta/hurdle model 2: -----------------------------------
#> Family: Gamma(link = 'log')
#> coef.est coef.se
#> (Intercept) 3.69 0.11
#>
#> Dispersion parameter: 0.75
#> Matérn range: 8.72
#> Spatial SD: 1.58
#>
#> ML criterion at convergence: 6381.834
#>
#> See ?tidy.sdmTMB to extract these values as a data frame.
fit <- sdmTMB(
density ~ 1,
data = pcod,
mesh = make_mesh(pcod, c("X", "Y"), cutoff = 10),
family = delta_poisson_link_lognormal(),
)
summary(fit)
#> Spatial model fit by ML ['sdmTMB']
#> Formula: density ~ 1
#> Mesh: make_mesh(pcod, c("X", "Y"), cutoff = 10) (isotropic covariance)
#> Data: pcod
#> Family: delta_poisson_link_lognormal(link1 = 'log', link2 = 'log')
#>
#> Delta/hurdle model 1: -----------------------------------
#> Family: binomial(link = 'log')
#> coef.est coef.se
#> (Intercept) -0.59 0.3
#>
#> Matérn range: 33.11
#> Spatial SD: 1.51
#>
#> Delta/hurdle model 2: -----------------------------------
#> Family: lognormal(link = 'log')
#> coef.est coef.se
#> (Intercept) 3.74 0.12
#>
#> Dispersion parameter: 1.33
#> Matérn range: 31.56
#> Spatial SD: 0.47
#>
#> ML criterion at convergence: 6265.205
#>
#> See ?tidy.sdmTMB to extract these values as a data frame. Created on 2023-08-15 with reprex v2.0.2 |
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Check against VAST. Check for anything that could still be causing under/overflows. Models frequently fall into optimization problems and are slower than I'd expect.
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