nlme and start=list()

Fri, Nov 22, 2002 9:29 AM

Dear Listers -

R1.61 on NT

We are trying to fit a polynomial usning nlme so that in ax^2+bx+c, c is 
fixed and a and b are random.

The data are
Frames = speed of flight (20-50)
Manlength = tail length (-20,0)
ID = individual (14 of them)

each individual has experienced each of 6 tail lengths in the range above 
and we are interested in the shape of the relationship between speed and 
manipulation.

using the following approach based on the Venables and Ripley (3rd ed) 
examples with the Sitka data set

nlme(Frames~a*Manlength^2+b*Manlength+c,
+ fixed=list(c~1),random=a+b~1|ID,
+ start=list(fixed=c(0.3,6,50)))

Error in nlme.formula(Frames ~ a * Manlength^2 + b * Manlength + c, fixed = 
list(c ~  :
         starting values for the fixed component are not the correct length

-realizing that something is wrong with how we have framed the start 
values... can anyone advise?

cheers
andrew

----------------------------------------------------------
Dr. Andrew Beckerman
Institute of Biological Science
University of Stirling
Stirling FK9 4LA
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nlme and start=list()

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