Re: [OPE-L] models with unequal turnover periods

From: Stephen Cullenberg (stephen.cullenberg@UCR.EDU)
Date: Thu Sep 06 2007 - 12:04:00 EDT

Stephen Cullenbnerg
College of Humanities Arts & Social Sciences
UC Riverside
-----Original Message-----
From: Michael Perelman <michael@ECST.CSUCHICO.EDU>
Date: Thursday, Sep 6, 2007 9:16 am
Subject: Re: [OPE-L] models with unequal turnover periods

Yes, Jerry, you get what I am arguing.  What is the turnover of equipment?  It depends upon new technology, market conditions, .....  You can look at the past & estimate that computers have turned over every 5 years, but a 10 year old computer might be just fine for typing a term paper.  Also, equipment is often put to good use after it is obsolete for some purposes.  For example, old tractors in California are still used for hauling irrigation pipes.

On Thu, Sep 06, 2007 at 11:48:33AM -0400, glevy@PRATT.EDU wrote:
 > Still playing on my one string violin, what about cases when the turnover
 > period for constant capital is unknown?

> Hi Michael P:

> Then you include it as a variable with an unknown magnitude in the model.
 There are different ways in which this could be done: e.g. one could make
 certain assumptions that could give you a _range_ for the variable.  This
 would, of course, introduce uncertainty into the model and mean that it
 wouldn't yield a single result.  Yet, this is uncertainty which is a
 consequence of the essential nature of the subject matter: i.e. it is
 _real_ uncertainty and shouldn't be eliminated for purposes of
 mathematical convenience.

> In solidarity, Jerry

Michael Perelman
Economics Department
California State University
Chico, CA 95929

Tel. 530-898-5321
E-Mail michael at

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