[Limdep Nlogit List] Marginal Effects in Truncation/Tobit Model

[Kalyan Chakraborty]

Hi Limdep Users,

I have one quick question about the output from marginal effects from Truncate Regression. I have a panel data for 14 firms over 4 year period and the data are arranged by year. For example, first 14 rows denote data on Y and X variables for 14 firms for Year-1, the second 14 rows are for Year-2 and so on. I have a total of 56 rows. Most of the X variables are in percent. The dependent variable (Y) takes any random value between 0.30 and 1.00 (efficiency scores from a DEA model). I prefer to use Truncation command specified on page-R17-73 (Version-9).

TRUNCATION;LHS=Y
	; RHS= X1,X2,X3,X4,X5,DUMM; FEM; MARGINAL EFFECTS; PDS=4 ; LIMITS=.3,1$ 
  
I tried both FEM and REM models but the problem is the beta coefficients are identical to marginal effects. I also found that 1 is being used as a scale factor for calculating partial derivatives in marginal effects. According to the manual marginal effects could be close to estimated parameters for a best fit model but there is no mention about exactly identical numbers. Similar results are obtained in a Tobit model using the same data.

Any help would be appreciated.

Thank you.

Kal


Kalyan (Kal) Chakraborty, Ph.D
Associate Professor (Economics)
http://www.emporia.edu/~chakrabk/
Department of Accounting Information Systems
School of Business
Emporia State University
1200 Commercial Street, Box 4057
Emporia, KS 66801
(Tel) 620-341-5913
(Fax) 620-341-6346
e-mail: kchakrab at emporia.edu