In respect of fitting piecewise linear regressions, have you looked at
the "segmented" package?
cheers,
Rolf Turner
On 18/01/12 04:30, crimsonengineer87 wrote:
Dear Forum,
I have been wracking my head over this problem for the past few days. I have
a dataset of (x,y). I have been able to obtain a nonlinear regression line
using nls. However, we would like to do some statistical analysis. I would
like to obtain a confidence interval for the curve. We thought we could
divide up the curve into piecewise linear regressions and compute CIs from
those portions. There is a package called strucchange that seems helpful,
but I am thoroughly confused.
'breakpoints' is used to calculate the number of breaks in the data for
linear regressions. I have the following in my script:
bp.pavlu<- breakpoints(Na ~ f(yield, a, b), h=0.15, breaks=3,
data=pavludata)
plot(bp.pavlu)
breakpoints(bp.pavlu)
But I am confused as to how to graph the piecewise functions that make up
the curve. I am not even sure if I am using breakpoints correctly. Do I just
give it a linear relationhip (Na ~ yield), instead of what I have?
Is there an easier way to calculate the confidence interval for a non-linear
regression?
I am new to R (as I've read in many questions), but I have most certainly
tried many things and am just getting frustrated with the lack of examples
for what I'd like to do with my data... I'd appreciate any insight. I can
also provide more information if I am not clear. Thanks in advance.
______________________________________________
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
