Insufficient observations

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eviewsnc
Posts: 7
Joined: Tue Nov 10, 2015 4:21 am

Insufficient observations

Postby eviewsnc » Tue Jul 17, 2018 3:05 am

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.
Attachments
Fertility_eviews.WF1
(9.81 KiB) Downloaded 11 times

startz
Non-normality and collinearity are NOT problems!
Posts: 3379
Joined: Wed Sep 17, 2008 2:25 pm

Re: Insufficient observations

Postby startz » Tue Jul 17, 2018 5:57 am

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.

eviewsnc
Posts: 7
Joined: Tue Nov 10, 2015 4:21 am

Re: Insufficient observations

Postby eviewsnc » Tue Jul 17, 2018 6:25 am

startz wrote: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.

eviewsaoa
Posts: 1
Joined: Tue Jul 17, 2018 7:59 am

Re: Insufficient observations

Postby eviewsaoa » Tue Jul 17, 2018 8:22 am

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.


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