I haven't played with this for a decade or so, but I believe you can do something with pdBlocked(). Possibly ask over on R-sig-ME as this quickly gets beyond the R-help level.
(Also, you are aware that it is not about what you want to estimate, but whether you believe the correlations are nonzero?) -pd > On 16 Jun 2018, at 13:00 , Chris Stride <c.b.str...@sheffield.ac.uk> wrote: > > Hi > > I'm trying to fit a mixed effects exponential decay model, in which I have > random effects for the initial value (init), the asymptote (asymp), and the > rate (rate). > > The catch is that I'd also like to estimate the correlation between init and > asymp, but not between init and rate, or asymp and rate. > > Now using random = pdDiag(init + asymp + rate ~ 1) has none of the random > effects correlated > > And using random = pdSymm(init + asymp + rate ~ 1) has all three of the > random effects correlated > > How do I specify just the correlation I want? > > cheers > > Chris > > ______________________________________________ > R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see > 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. -- Peter Dalgaard, Professor, Center for Statistics, Copenhagen Business School Solbjerg Plads 3, 2000 Frederiksberg, Denmark Phone: (+45)38153501 Office: A 4.23 Email: pd....@cbs.dk Priv: pda...@gmail.com ______________________________________________ R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see 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.
