Hello R gurus,

I am trying to characterize temporal trends in a water quality dataset that includes repeated samples from several stations over a ten year period. I fit the following mixed effects model:
lmer(logDIN~Depth+Date+(1|ID)+(0+Depth|ID)+(0+Date|ID))

A significant geomorphic change happened at Date=2.7 which is suspected to have changed the slope of the trend. I would like to fit a piecewise model with separate slopes before and after the break. I suspect this may require using nlmer, but can't figure out the model syntax. Any advice would be greatly appreciated.

Matt
_______________________
Matt Diebel, Ph.D.
The Cadmus Group, Inc.
301 N. Broom St., Suite 201
Madison, WI 53703
Office: 608-250-1974
Mobile: 608-516-0518


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