Suppose you want to fit some nonlinear model for the median or the 95th
quantile. For instance, suppose you believe that the 95th quantile of
the calcium/creatinine ratio, Y, may be modeled as the following function
of age (X):
Y = C0 + (B0 + Bl * X + B2 * X^2) * exp(-A0 * X )
where A0, B0, B1, B2, C0 are the coefficients that you'd like to estimate.
Is there a way to do this in Stata?
(For comparison of software packages: I did manage to do this in R, using
the quantreg package. But it would be nice to be able to do this in Stata,
among other reasons because Stata has a nice built-in bootstrap option.)
(Reference for the nonlinear function: V. Matos, 1997, J Pediatr 131:252-7)
Thanks for any advice
Jacob Wegelin
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