[R] Finding starting values for the parameters using nls() or nls2()

[dave fournier]

  Unfortunately this problem does not appear to be well posed.

     Retention = (b0*Area^(th+1))^b

If b0, th, and b are the parameter only the product (th+1)*b is determined.

This comes from noting that powers satisfy



     (a^b)^c  =  a^(b*c)



So your model can be written as



           (b0^b) * Area^((th+1)*b)