>Dear r-help members
>I posted this message already yesterday, but don't know whether it
>reached you since I joined the group only yesterday.
>I would like to estimate the boxcox transformed model
> (y^t - 1)/t ~ b0 + b1 * x.
>Unfortunately, R returns with an error message when I try to
>perform this with the call
>nls( I((y^t - 1)/t) ~ I(b0 + b1*x),
> start = c(t=1,b0=0,b1=0), data = mydataframe)
>The error message is: Object "t" not found
>Apparently R seems not to accept parameters on the left hand
>side of a regression model. I know that my do-it-yourself
>strategy is not necessary, since the package box-cox is
>available. Unfortunately, I want the use the box-cox
>transformation in a quantile regression, i.e. I have to replace
>nls by nlrq in the call above.
>Any suggestions?
>Thanks and best regards,
> Johannes Ludsteck
You suggest the solution yourself: transform the equation to have all
parameters at the right, thus:
y ~ ((b0 + b1 * x) * t + 1) ^ 1/t
(double check if this is correct)
Best,
Philippe Grosjean
...........]<(({?<...............<?}))><...............................
) ) ) ) )
( ( ( ( ( Dr. Philippe Grosjean
) ) ) ) )
( ( ( ( ( Numerical Ecology Laboratory
) ) ) ) ) Mons-Hainaut University
( ( ( ( ( 8, Av. du Champ de Mars, 7000 Mons
) ) ) ) ) Belgium
( ( ( ( (
) ) ) ) ) e-mail: [EMAIL PROTECTED]
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) ) ) ) )
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