Dialogue

[saeed@ait.ac.th (Prof Khalid Sae]

I wish to add to Jacks comment that reference mode is a pattern not
numbers, although numbers may describe this pattern. Data for reference
mode may reside in numbers or in qualitative information but it must be
able to deliver the pattern in question. Discerning this pattern is really
a modeling process that is conducted in SD practice to date at a conceptual
level. I have attempted to illustrate this point in a paper:

The organization of learning in System Dynamics Practice

that I presented at the Tokyo SD conference.

Policy design is not hampered by not having numbers in the refernce mode if
policy objective is to influence day-by-day decisions and not a blind
exogeneous intervantion based on forecating.

I also recommend highly Jacks article in SDR 12(1).


Khalid
saeed@ait.ac.th

Professor Khalid Saeed
Infrastructure Planning & Management
School of Civil Engineering
ASIAN INSTITUTE OF TECHNOLOGY
G.P.O. Box 2754, Bangkok, THAILAND
phones: (66-2)524-5681, (66-2)524-5785; fax: (66-2)524-5776