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modSel {unmarked}

Model selection results from an unmarkedFitList
Package: 
unmarked
Version: 
0.10-3

Description

Model selection results from an unmarkedFitList

Arguments

         

object
an object of class "unmarkedFitList" created by the function      fitList.
nullmod
optional character naming which model in the     fitList contains results from the null model. Only used in         calculation of Nagelkerke's R-squared index.     

Values

A S4 object with the following slots          

Full
data.frame with formula, estimates, standard errors and model         selection information. Converge is optim convergence code. CondNum is         model condition number. n is the number of sites. delta is delta AIC.         cumltvWt is cumulative AIC weight. Rsq is Nagelkerke's (1991) R-squared index, which is only returned when the nullmod argument is specified.
Names
matrix referencing column names of estimates (row 1) and      standard errors (row 2).

References

Nagelkerke, N.J.D. (2004) A Note on a General Definition of the     Coefficient of Determination. Biometrika 78, pp. 691-692.

Note

Two requirements exist to conduct AIC-based model-selection and model-averaging in unmarked. First, the data objects (ie, unmarkedFrames) must be identical among fitted models. Second, the response matrix must be identical among fitted models after missing values have been removed. This means that if a response value was removed in one model due to missingness, it needs to be removed from all models.

Examples

data(linetran)
(dbreaksLine <- c(0, 5, 10, 15, 20)) 
lengths <- linetran$Length * 1000
 
ltUMF <- with(linetran, {
    unmarkedFrameDS(y = cbind(dc1, dc2, dc3, dc4), 
    siteCovs = data.frame(Length, area, habitat), dist.breaks = dbreaksLine,
    tlength = lengths, survey = "line", unitsIn = "m")
    })
 
fm1 <- distsamp(~ 1 ~1, ltUMF)
fm2 <- distsamp(~ area ~1, ltUMF)
fm3 <- distsamp( ~ 1 ~area, ltUMF)
 
fl <- fitList(Null=fm1, A.=fm2, .A=fm3)
fl
 
ms <- modSel(fl, nullmod="Null")
ms
 
coef(ms)                            # Estimates only
SE(ms)                              # Standard errors only
(toExport <- as(ms, "data.frame"))  # Everything

Author(s)

Richard Chandler rbchan@uga.edu

Documentation reproduced from package unmarked, version 0.10-3. License: GPL (>= 3)