Inf in regressions

you could use:

lm( y ~ x + z + log(w), subset = w > 0)


I hope it helps.

Best,
Dimitris

----
Dimitris Rizopoulos
Ph.D. Student
Biostatistical Centre
School of Public Health
Catholic University of Leuven

Address: Kapucijnenvoer 35, Leuven, Belgium
Tel: +32/(0)16/336899
Fax: +32/(0)16/337015
Web: http://www.med.kuleuven.be/biostat/
     http://www.student.kuleuven.be/~m0390867/dimitris.htm


----- Original Message ----- 
From: "Dimitri Szerman" <dimitrijoe at ipea.gov.br>
To: "R-Help" <r-help at stat.math.ethz.ch>
Sent: Tuesday, October 25, 2005 4:47 PM
Subject: [R] Inf in regressions

Hi,

Suppose I I wish to run

lm( y ~ x + z + log(w) )

where w assumes non-negative values. A problem arises when w=0, as 
log(0)
= -Inf, and R doesn't accept that (as it "accepts" NA). Is there a 
way to
tell R to do with -Inf the same it does with NA, i.e, to ignore it? 
(
Otherwise I have to do something like

w[w==0] <- NA

which doesn't hurt, but might be a bit incovenient sometimes.)

Thanks in advance.

Dimitri

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