[R-sig-ME] nlmer self starting function

[Daniel Hocking]

I am trying to use the following nlmer function to estimate random break points in a polynomial smooth break point regression (sense Hout et al. 2011: http://onlinelibrary.wiley.com.silk.library.umass.edu/doi/10.1002/sim.4127/abstract)

nl1 <- nlmer(Reaction ~ SSPoly(Days,n0,n1,n2,n3) ~ (n0|Subject)+(n1+n2|Subject)+(n3|Subject), data=sleepstudy, start = c(n0=22, n1=0, n2=-1, n3=-4))

I get the error: Error in eval(expr, envir, enclos) : could not find function “SSPoly"

I assume this is due to changes in lme4 versions. I am not experienced with the nlmer function and writing custom functions and start functions. Does anyone have recommendations on the easiest way to implement this model (preferable without going to WinBUGS/JAGS)?

Thanks,
Dan
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Daniel Hocking
Department of Environmental Conservation
Northeast Climate Science Center
University of Massachusetts

http://www.danieljhocking.wordpress.com
dhocking at umass.edu
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