Here is a change required from MASS:::dropterm.glm() and

MASS:::addterm.glm().

Thanks

Marc

The stepAIC() function from package MASS uses extractAIC() to get the

AIC from a model.

Several methods exist:

extractAIC.glm() for example, some in MASS packages and some in stats

package.

The parameters for extractAIC() are:

fit, scale, k = 2, ...

The ... are not used in most of the extractAIC.xxx() methods, from

example in stats:::extractAIC.glm() or MASS:::extractAIC.loglm() but its

presence could be necessary if extractAIC() is changed to use for

example to use AICc rather than AIC.

Within stepAIC(), extractAIC() uses always the ... parameter. So all is

ok for that.

However, stepAIC() uses dropterm() or addterm().

Within MASS:::dropterm.glm() and MASS:::addterm.glm(), extractAIC() is

also used but without the ... parameter.

It prevents to use new version of extractAIC() that could use this

parameter.

The solution is simple:

In MASS:::dropterm.glm(), line 60 and MASS:::addterm.glm(), line 84:

aic <- aic + (extractAIC(object, k = k)[2L] - aic[1L])

must be changed to

aic <- aic + (extractAIC(object, k = k, ...)[2L] - aic[1L])

Other dropterm.xxx() and addterm.xxx() do not suffer this problem.

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