EViews.com

Dear all,

I am trying to estimate a fertility curve, using the data in the attached workfile.

I am trying to estimate the following equation using least squares (other estimation methods also do not yield results).

equation eq1.ls fertility=c(1)*(c(2)/c(3))*(c(3)/age)^(3/2)*exp(-(c(2))^2*(c(3)/age+age/c(3)-2))

I keep getting an error message saying I have insufficient observations, which I don't understand. Any assistance would be greatly appreciated.

EViews starts estimation with whatever is stored in the c vector. In your case, this is causing some division by zero. Try saying before you start the estimation.

EViews starts estimation with whatever is stored in the c vector. In your case, this is causing some division by zero. Try saying

Code: Select all

c = 1

before you start the estimation.

Many thanks Startz, works perfectly.

Dear all,

I've encountered the same issue, so your answer was very useful - many thanks for that.

Based on the workfile attached in this thread, I have a question concerning the starting point values. I have set the following equation and starting point values, which should be close enough to the actual curve:

param c(1) 1 c(2) -.15 c(3) 30 c(4) 8

equation eq1.ls fertility=2*c(4)^(-1)*exp(-(age-c(3))/c(4))/((1+exp(-(age-c(3))/c(4)))^2*(1+exp(-c(1)*((age-c(3))/c(4))-c(2)*((age-c(3))/c(4))^3)))


However, when I change these values, I do not get any changes in the estimated coefficients (which I would expected). Also, even if I close and open the program, I get convergence all the time in the same number of iterations. I wouldn't have expected this -maybe I'm thinking in terms of the "Solver" addin of Excel, and that's confusing me (relatedly, the estimation I get through Solver by minimizing the SSR is much closer to the actual figure compared to what I get in Eviews).

Any help would be highly appreciated.

Thanks in advance.