# Re: st: RE: xtabond2 and parameter restrictions

 From "Mark Schaffer" <[email protected]> To [email protected] Subject Re: st: RE: xtabond2 and parameter restrictions Date Thu, 07 Jul 2005 11:24:58 +0100

Wim, Julian,

Subject:        	st: RE: xtabond2 and parameter restrictions
Date sent:      	Thu, 7 Jul 2005 10:47:56 +0200
From:           	"Gielis Wim" <[email protected]>
To:             	<[email protected]>

> Hi Statalisters,
>
> I think you can do this by stating:
>
> define 1 xy = z
> define 2 xp = q
>
> (I abbreviate the variable names into p, q, x, y, z for convenience)
>
> After that, you type the command for xtabond2, with
>
> const(1 2)
>

I am pretty sure that xtabond2 doesn't support constraints.

--Mark

> BUT (I face a similar problem)
>
> 1) what to do if the restrictions you want to impose involve parameters
> outside the relation (e.g. a coefficient represents the ratio of a
> coefficient in the relation and the price elasticity of demand)???
>
> 2) going further, how can you obtain point estimates, standard errors,
> etc. for all these variables (so including price elasticity of
> demand)???
>
> Regards,
>
> Wim
>
>
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]] On Behalf Of julian
> estevez
> Sent: donderdag 7 juli 2005 2:23
> To: [email protected]
> Subject: st: xtabond2 and parameter restrictions
>
> Dear Statalisters:
>
> I am estimating a Dynamic Panel Data model using xtabond2
>
> It is of the form:
>
> Dependent variable(i,t)  = constant +b1 X1(i,t) + b2 X1(i,t-1)+ b3
> X2(i,t) +
> b4 X2(i,t-1) + b5 Dependent variable(i,t-1) + disturbance
>
> I wonder how I can estimate the model but including the following
> parameter
> restrictions:
>
> b5 b1 = b2
> b5 b3 = b4
>
> Ignoring these restrictions mean that I am loosing information because I
> am overparametrizing the model. I would greatly appreciate if somebody
> could tell me how to combine parameter restrictions with xtabond2, or
> some other solution to my problem
>
> Regards
>
> Julian
>
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Prof. Mark E. Schaffer
Director
Centre for Economic Reform and Transformation
Department of Economics
School of Management & Languages
Heriot-Watt University, Edinburgh EH14 4AS  UK
44-131-451-3494 direct
44-131-451-3296 fax