Hello:
I hope that someone more knowledgeable will confirm or correct
what I'm about to say. I don't have time now to check this by studying
the pspline code.
From reading the pspline{survival} help page, I believe it uses
standard B-splines, penalising the integrated second
The pspline function uses P-splines (Eilers and Marx, Statistical
Science, 1981), which are a spline basis using a regular set of knots.
Looking at the code for pspline, which isn't so hard, let
dx = (max(x) - min(x))/ ntermwhere nterm is round(2.5 * desired
degrees of freedom)
Hi All,
I am trying to figure out how to get the position of the knots in a pspline
used in a cox model.
my.model = coxph(Surv(agein, ageout, status) ~ pspline(x), mydata) # x being
continuous
How do I find out where the knot of the spline are? I would like to know to
figure out how many
On Nov 17, 2010, at 1:05 PM, Federico Calboli wrote:
Hi All,
I am trying to figure out how to get the position of the knots in a
pspline used in a cox model.
As far as I understand it, the term knot should be used with natural
splines, but not for penalized smoothing splines. See p 124
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