Anutechia,
What John's saying is that you need a model (ie, an estimating equaion) for the
relationship between TC and LC. Suppose it's a simple linear relationship:
TC = a + b*LC + u
where a is a constant and u is an unpredictable error term. Then just
regressing TC on LC in gretl will give you the marginal effect as the estimated
value of b. More complicated models might include powers of LC or other
variables. In those cases the marginal effects would be a bit more complicated.
For example, in a quadratic model
TC = a + b*LC + c*LC^2 + u
(ie, include squared labor costs), the marginal effect would be b+2*c*LC (so
the marginal effect depends on the level of LC). You might want to have a look
at a basic econometrics text like Stock & Watson for more details on
interpreting regressions.
Good luck!
PS
________________________________
From: gretl-users-bounces(a)lists.wfu.edu [gretl-users-bounces(a)lists.wfu.edu]
on behalf of Anutechia Asongu [simplice_peace(a)yahoo.com]
Sent: Monday, July 25, 2011 5:59 PM
To: Gretl list
Subject: Re: [Gretl-users] First derivation series
Dear John C Frain,
I'm afraid, I can't grasp a detail in what you just
disclosed. Does estimation of the required marginal effect synonymous to
obtaining a series for the marginal effect?
Thanks
--- On Mon, 7/25/11, John C Frain <frainj(a)gmail.com> wrote:
From: John C Frain <frainj(a)gmail.com>
Subject: Re: [Gretl-users] First derivation series
To: "Gretl list" <gretl-users(a)lists.wfu.edu>
List-Post: gretl-users@gretlml.univpm.it
Date: Monday, July 25, 2011, 2:32 PM
You must first specify some structural equation for the relationship between TC
and LC, (and other relevant variables). Estimate this relationship using
gretl. (How you do this depends on your model and the possible presence of
other endogenous models.) You can then easily estimate the required marginal
effect.
Best regards
John
On 25 July 2011 21:28, Anutechia Asongu
<simplice_peace(a)yahoo.com<UrlBlockedError.aspx>> wrote:
Hi all,
Say I have a two series: Total Cost(TC) and Labour Cost(LC). I wish to
obtain another series for the partial derivative of TC with respect to LC
(dTC/dLC). Any hint on how this could be done via Grelt.
Thanks
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John C Frain
Economics Department
Trinity College Dublin
Dublin 2
Ireland
www.tcd.ie/Economics/staff/frainj/home.html<http://www.tcd.ie/Economics/staff/frainj/home.html>
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