From wuolong at gmail.com  Fri Dec 22 20:16:02 2006
From: wuolong at gmail.com (Michael)
Date: Fri, 22 Dec 2006 13:16:02 -0600
Subject: [Rd] variable scope in update(): bug or feature?
References: <c2hcvp2n40.fsf@bass.biostat.umn.edu>
	<17803.38033.644533.557922@stat.math.ethz.ch>
	<u03b77olqx.fsf@gmail.com>
	<Pine.LNX.4.64.0612221818570.20903@gannet.stats.ox.ac.uk>
Message-ID: <rrk60jn3m5.fsf@gmail.com>

On 22 Dec 2006, Brian Ripley wrote:

> 'update' will update and (by default) re-fit a model. It does this
> by extracting the call stored in the object, updating the call and
> (by default) evaluating that call. Sometimes it is useful to call
> 'update' with only one argument, for example if the data frame has
> been corrected.

Thanks.  I understand now that this is the expected behavior per the
documentation.

It is just that when I call 'update (m1, ~ . - z)' I did not expect x to
change (or everything can be different if mydata has changed).  I only
wanted to evaluate the old model with old data but sans the z variable.

Would it be useful to have an option in update() not to update the data
(i.e., behaves more like drop1())?

Michael



[Rd] variable scope in update(): bug or feature?
Michael