# Re: st: reg3 or xt for simultaneous equation model with panel data and lagged effects?

 From Rajiv Sabherwal To statalist@hsphsun2.harvard.edu Subject Re: st: reg3 or xt for simultaneous equation model with panel data and lagged effects? Date Fri, 23 Feb 2007 21:31:17 -0600

Hello,

I had earlier sent the message below to statalist. However, a few minutes ago, it struck me that the equations I have may not be a "simultaneous equation model" at all. This is based partly on Kit Baum's message on http://www.stata.com/statalist/archive/2004-03/ msg01120.html.

In our model (given below), none of the endogeneous variables affect each other at that time. All the variables on the right-hand sides of all equations are either exogneous of lagged-endogeneous (i.e., pre- determined).

Therefore, it would seem that simple panel regressions, rather than simultaneous models, would be appropriate. Am I missing something?

Thanks, and best wishes,

Rajiv

On Feb 23, 2007, at 1:25 PM, Rajiv Sabherwal wrote:

Hello,

A PhD student and I are trying to test a model containing simultaneous equations such as the following:

y1(t) = a1 + b11*y1(t-1) + b12*y2(t-1) +b13*y3(t-1) + b14*y4(t-1) + b15*y5(t-1) + b16*x1 + b17*x2
y2(t) = a2 + b21*y2(t-1) + b23*y3(t-1) + b24*y4(t-1) + b25*y5(t-1) + b26*x1 + b27*x2
y3(t) = a3 + b31*x3 + b32*x4 +b33*x5
y4(t) = a4 + b41*x6 + b42*x7
y5(t) = a5 + b51*x8 + b52*x9

We have panel data, with 5000 units observed at 50 periods each, and some time-invariant exogeneous variables characterizing each unit. None of the exogeneous variables vary over time, but all the endogeneous variables do.

We believe random effects would be appropriate as we also need to study the effects of the time-invariant exogeneous variables. We are contemplating using reg3 (I couldn't find an appropriate xt command, as xtivreg and xtivreg2 seem to be for a single endogeneous variable). Would reg3 be appropriate for this situation? Also, how would we identify the panel variable in reg3?

I have searched the internet and Stata discussion lists, but could not find an answer. I did find the following paper, which uses reg3, but with fixed effects and no time-invariant exogeneous variables.

Why Firms Want to Organize Efficiently and What Keeps Them from Doing so: Inappropriate Governance, Performance, and Adaptation in a Deregulated Industry, Jack A. Nickerson; Brian S. Silverman, Administrative Science Quarterly, Vol. 48, No. 3. (Sep., 2003), pp. 433-465.

Rajiv

----
Rajiv Sabherwal, Ph.D.
University of Missouri Curators Professor
University of Missouri, St. Louis
St. Louis, MO 63121

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