[proFit-list] statistically valid fit?

[Bruce Palfey]

I have data from kinetics experiments that I'd like to fit.  The  
differential equations describing the mechanism can be integrated,  
but the resulting equation is unusual; it cannot be expressed as  
concentration as a function of time.  However, it can be manipulated  
to give   t = F(concentration).  It would be easy to fit data in pro  
Fit to this equation.  But...

But this is wrong statistically, isn't it?  In my case, t is the  
(experimental) independent variable, and the error on it is very  
small compared to the error on the (experimental) dependent variable  
- the concentration.  Isn't it improper to use standard fitting  
algorithms in such a case, i.e., isn't it implicitly assumed that the  
error on the independent variable is negligible?  Unfortunately, I  
can't transform my function so that concentration = f(t).

Any thoughts on how to obtain valid fits with valid errors on the  
parameters?

ciao,
Bruce