Dear List,
I want to ask a AIC question based on package library(MuMIn)
The relative importance of 16 explanatory variables
are assessed using delta AIC in a generalized linear model.
Please kindly advise if it is possible to show models
with any two only certain variables.
Thank you.
Elaine
I asked a similar question and got a great help for models
with only one variable as below.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In effect, you want
data(Cement)
lm1 <- lm(y ~ ., data = Cement)
dd <- dredge(lm1, subset = X1)
want <- with(dd, is.na(X) & is.na(X2) & is.na(X3) & is.na(X4))
want
## how many models selected?
sum(want)
## OK selected just 1, show it
dd[want, , drop = FALSE]
Oh, actually, I suppose you could automate this, so it will return all
models with single variable:
dd <- dredge(lm1)
parms <- !is.na(dd[, -c(1, (ncol(dd) - c(0:7)))])
want <- which(rowSums(parms) == 1)
dd[want, ]
Having said all this, I don't think this is a good way to do model
selection.
G
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