From Berwin.Turlach at gmail.com  Fri Jan 20 07:42:08 2012
From: Berwin.Turlach at gmail.com (Berwin A Turlach)
Date: Fri, 20 Jan 2012 14:42:08 +0800
Subject: [Rd] nobs() and logLik()
In-Reply-To: <4F1907AE.3090302@stats.ox.ac.uk>
References: <20120120133014.56c9fd05@bossiaea>
	<4F1907AE.3090302@stats.ox.ac.uk>
Message-ID: <20120120144208.2d6fdfed@bossiaea>

G'day Brian,

On Fri, 20 Jan 2012 06:20:30 +0000
Prof Brian Ripley <ripley at stats.ox.ac.uk> wrote:

> I do wonder why people use zero weights rather than 'subset', and I 
> don't particularly like the discontinuity as a weight goes to zero.

I completely agree, and for developers it is a bit of a pain to make
sure that all possible combinations of 'subset' and 'weights' play
"nicely" together.

One reason that I can see for people to use zero weights rather than
'subset' is that fitted() and predict() in the former case readily
produce fitted values for the observations that received a zero weight.

Cheers,

	Berwin



[Rd] nobs() and logLik()
Berwin A Turlach