Stocks, flows, CLDs, +/-, Ss/Os, and u-shaped arrows

[Bill Braun]

Hello George,

Two thoughts/questions...

Cannot some of the ambiguity between 1) the cause is additive or
subtractive and 2) a change in A causes a change int he same direction in B
be resolved by being more explicit in the naming of the variables. If the
variable carries a name that makes it clear it is a flow, would not the CLD
be more representative of what the modeler wants to say?

I am reading your book Intro to SD Modeling with Dynamo and you use a
hybrid diagram as an example of the "best of both worlds" (at least I read
it that way). Is there a defacto assumption that CLD and SD need to be
"pure" in their use?

And, is this indeed a step toward the desired result, or the invitation to
another set of communication difficulties?

Bill
Bill Braun <medprac@hlthsys.com>
---------------------------
Medical Practice Systems Inc. (216) 382-7111 (Voice)
and The Health Systems Group http://www.hlthsys.com
Mergers - Planning - Management Services
Marketing - Managed Care - Education & Training

[Phil Odence]

>If the
>variable carries a name that makes it clear it is a flow, would not the CLD
>be more representative of what the modeler wants to say?

I agree with the spirit, Bill, but I think the answer is to use a symbol
to indicate whether the variable is a stock of flow, and to show the
direction of flow...i.e. a stock/flow diagram.

***************************************************************************

Phil Odence
High Performance Systems
45 Lyme Road, Suite 200
Hanover, NH 03755-1221
voice- 603 643 9636 x107, fx- 603 643 9502, web- http://www.hps-inc.com