Message-ID: <2371c22294.222942371c@jhsph.edu>
Date: 2003-06-05T16:01:56Z
From: Ravi Varadhan
Subject: na.action in model.frame
Dear Group:
I am trying to create a model frame from a formula for the model as
follows:
formula <- y ~ x1 + x2 + x3
X <- model.frame(form=formula,data=mydata)
I have some missing values in some the variables, but I want them to be
included in my model frame and to be indicated as "NA". Is there a way
to do this?
thanks,
Ravi.