From kwright at eskimo.com  Mon Apr 18 20:55:24 2005
From: kwright at eskimo.com (kwright@eskimo.com)
Date: Mon Apr 18 20:55:35 2005
Subject: [Rd] Why no BIC.default function?
In-Reply-To: <Pine.LNX.4.61.0504181925230.17897@gannet.stats>
References: <17905.170.54.59.167.1113847926.squirrel@170.54.59.167>
	<Pine.LNX.4.61.0504181925230.17897@gannet.stats>
Message-ID: <31605.170.54.59.167.1113850524.squirrel@170.54.59.167>

> R does not have a BIC S3 generic function: it is in package nlme!
> (There is one for S4 classes in package stats4.)

Sorry, I should have noticed that.  Maybe my question should have been:

Since the stats package has generics for logLik and AIC, could it include
a generic for BIC?

Kevin Wright

>> I'm using R 2.0.1.
>>
>> I looked in the email archives but didn't see anything on this topic.
>>
>> I've noticed a surprising (to me) difference between AIC and BIC:
>>
>>> methods("AIC")
>> [1] AIC.default* AIC.logLik*
>>
>>> methods("BIC")
>> [1] BIC.gls*    BIC.lm*     BIC.lme*    BIC.lmList* BIC.logLik* BIC.nls*
>>
>> The BIC.gls BIC.lm BIC.lme BIC.lmList and BIC.nls functions appear to
>> have
>> exactly the same definition.  (I didn't check with 'diff' though.)
>>
>> Would it make sense to treat BIC similarly to AIC and have just
>> BIC.default and BIC.logLik?
>
> --
> Brian D. Ripley,                  ripley@stats.ox.ac.uk
> Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
> University of Oxford,             Tel:  +44 1865 272861 (self)
> 1 South Parks Road,                     +44 1865 272866 (PA)
> Oxford OX1 3TG, UK                Fax:  +44 1865 272595
>


[Rd] Why no BIC.default function?
kwright@eskimo.com