Stochastic production frontier

[Pontus Mattsson]

Hi, I am trying to perform model 3: Half-normal stochastic production frontier model from the book "Stochastic frontier analysis using Stata" (page 292).

I would like to do the sfmodel command in order to do decomposition of TFP later. The first part is like this:
sfmodel lny, prod dist(h) frontier(lnl lnk lnl2 lnk2 lnllnk t tt tll tlk) usigmas(t) vsigmas()
sf_init, frontier(b1) usigmas(0 0) vsigmas(0)
ml max, difficult gtol(1e-5) nrtol(1e-5)

lnl is the log of labor, lnk log of capital, lnl2 and lnk2 is lnl*lnl*0.5 and similarly for lnk. t is a time variable (year in my case) and tt is t*t*0.5. Others are similar interactions.
The problem in the first step which becomes problem later is that t is omitted due to collinearity. I do not know why.

A second question is regarding usigmas(0 0) in the command sf_init. Then I get the answer: "initial vector: matrix must be dimension 12".

THanks in advance

[Pontus Mattsson]

Anyone that can help ?

[Rogers Ochenge]

Hi how do you obtain this user written command sfmodel?

[Thierry Coulibaly]

Hi, I hope you find a solution for your problem. I have also a problem with the command sfmodel, I used findit sfmodel, but impossible to find it. Is the command sfmodel still available?

[Thierry Coulibaly]

I fnally find it, there is link at the beginning of the book A practitioner's Guide for stochastic frontier analysis using Stata. If you follow the link, you will find the do files, ado files and the data. Just download and copy the ado files in your adopath.

[Yao Shi]

I fnally find it, there is link at the beginning of the book A practitioner's Guide for stochastic frontier analysis using Stata. If you follow the link, you will find the do files, ado files and the data. Just download and copy the ado files in your adopath.

Dear Dr. Coulibaly,
I am facing the same problem, but the link on the book is broken. Could you please send me the files?

Many thanks,
Yao Shi

[Yao Shi]

Dear Dr. Coulibaly,
I am facing the same problem, but the link on the book is broken. Could you please send me the files?

Many thanks,
Yao Shi

I have found it through Professor Hung-Jen Wang's personal webpage:

https://homepage.ntu.edu.tw/~wangh/book-software.html

Copied text for instructions:

1. Copy and paste one of the following lines (in one line) to Stata's Command window and execute it.
   • net install sfbook_install, from(http://homepage.ntu.edu.tw/~wangh/sfbook/) replace
2. Execute the following command in Stata.
   "sfbook_install"
   It will install the programs (*.ado files) to Stata's PLUS directory, and copy the demo files (*.do, *.dta) to c:\sfbook_demo for Windows and /users/`c(username)'/sfbook_demo for Mac.
3. After the programs are installed, you may use "help sfbook" to see a short description on the installed Stata commands.