Search found 21 matches
- Sat Jul 12, 2008 7:13 am
- Forum: SD Mailing List Archive
- Topic: QUERY Society Strategy Development
- Replies: 127
- Views: 143348
QUERY Society Strategy Development
Posted by ""Jack Homer"" <jhomer@comcast.net> More grist for Kim Warren's mill regarding society strategy development: One thing that I believe has not come up in the discussion so far is the question of our true current status as a field. If we're talking about visions and goals...
- Sat Jul 12, 2008 7:13 am
- Forum: SD Mailing List Archive
- Topic: QUERY European 'Global System Dynamics Project'
- Replies: 13
- Views: 11651
QUERY European 'Global System Dynamics Project'
Posted by ""Jack Homer"" <jhomer@comcast.net> Jim Thompson writes: ""Environmental science, climatology, population studies, atmospheric sciences and associated fields already use 'dynamic systems' logic. From a gloss of the literature in those fields, the rigour applie...
- Sun Jul 06, 2008 7:07 am
- Forum: SD Mailing List Archive
- Topic: QUERY Cardiac defribillator adoption
- Replies: 2
- Views: 3892
QUERY Cardiac defribillator adoption
Posted by ""Jack Homer"" <jhomer@comcast.net> Kirandeep, My doctoral thesis at MIT presents a general theory of the emergence (adoption, modification, evolving use) of a new medical technology, including detailed application to cardiac pacemakers and the antibiotic drug clindamyc...
- Fri May 16, 2008 7:11 am
- Forum: SD Mailing List Archive
- Topic: QUERY Models, Problems and Systems
- Replies: 29
- Views: 98315
QUERY Models, Problems and Systems
Posted by ""Jack Homer"" <jhomer@comcast.net> Christina Spencer says: > I agree that it is perfectly reasonable that people with questions that > may have come up before should investigate before posting old questions Let me state again that I haven't asked newbies to investigate...
- Wed May 14, 2008 7:41 am
- Forum: SD Mailing List Archive
- Topic: QUERY Models, Problems and Systems
- Replies: 29
- Views: 98315
QUERY Models, Problems and Systems
Posted by ""Jack Homer"" <jhomer@comcast.net> Kim Warren writes: ""I'd just ask, though, that we not discourage people from resurrecting old questions [and answers]."" People should be encouraged to ask any question they want, and novices will, of course, end ...
- Sun May 11, 2008 7:13 am
- Forum: SD Mailing List Archive
- Topic: QUERY Models, Problems and Systems
- Replies: 29
- Views: 98315
QUERY Models, Problems and Systems
Posted by ""Jack Homer"" <jhomer@comcast.net> Jay Forrest writes: ""Discussions with clients who have used SD suggest to me that a significant portion of their failure to pursue SD over time is that they tend to find SD answers don't work over time - which is ultimately...
- Sat May 10, 2008 6:54 am
- Forum: SD Mailing List Archive
- Topic: QUERY Models, Problems and Systems
- Replies: 29
- Views: 98315
QUERY Models, Problems and Systems
Posted by ""Jack Homer"" <jhomer@comcast.net> Re: modeling problems rather than systems. I have been a little dismayed to see extended discussion of yet another question that was answered in our field decades ago; see, for example, Industrial Dynamics (JWF, 1961), section 5.1, pa...
- Tue Apr 22, 2008 7:23 am
- Forum: SD Mailing List Archive
- Topic: QUERY Meaning of Stock/Level
- Replies: 46
- Views: 38772
QUERY Meaning of Stock/Level
Posted by ""Jack Homer"" <jhomer@comcast.net> In regard to the definition of stocks, Jack Harich says: > That such contentious principles have not been nailed down would seem to > be an indicator of how young the field of system dynamics remains. This is a much more a reflection ...
- Thu Mar 13, 2008 6:57 am
- Forum: SD Mailing List Archive
- Topic: QUERY Definition of root cause
- Replies: 34
- Views: 30008
QUERY Definition of root cause
Posted by ""Jack Homer"" <jhomer@comcast.net> Jack Harich writes: > Page 86 of Sterman says ""Formulate a dynamic hypothesis that explains > the dynamics as endogenous consequences of the feedback structure."" > This implies that the definition of ""...
- Fri Mar 07, 2008 6:53 am
- Forum: SD Mailing List Archive
- Topic: QUERY Definition of root cause
- Replies: 34
- Views: 30008
QUERY Definition of root cause
Posted by ""Jack Homer"" <jhomer@comcast.net> Now that Jack Harich has clarified that he's looking for ""the key elements of the model [or, better, the real world or the problematic system] that cause it to behave the way it does"", I think we have an answer f...
- Tue Mar 04, 2008 7:54 am
- Forum: SD Mailing List Archive
- Topic: QUERY Definition of root cause
- Replies: 34
- Views: 30008
QUERY Definition of root cause
Posted by ""Jack Homer"" <jhomer@comcast.net> I don't see how Jack Harich's emphasis on root causes is helpful. Trying to find the ""true"" original or root causes in complex social systems (unlike engineered systems) is a fruitless endeavor, because when it c...
- Wed Feb 20, 2008 7:51 am
- Forum: SD Mailing List Archive
- Topic: QUERY The Minimum Acceptable Model Standard
- Replies: 18
- Views: 16788
QUERY The Minimum Acceptable Model Standard
Posted by ""Jack Homer"" <jhomer@comcast.net> Tom Forest's idea for minimum requirements for conference papers is interesting and could offer some needed guidance for reviewers. But, I think we'd have to exempt purely methodological (non-applied) papers from those requirements. F...
- Tue Nov 13, 2007 8:39 am
- Forum: SD Mailing List Archive
- Topic: QUERY Ensuring Quality of Models
- Replies: 13
- Views: 15758
QUERY Ensuring Quality of Models
Posted by ""Jack Homer"" <jhomer@comcast.net> Kim Warren cites Geoff Coyle: "".. A model should do what the real world does, and for the same reasons."" That's still not quite enough. The SD approach to model evaluation (as in Forrester and Senge 1980) also co...
- Sat Oct 06, 2007 7:55 am
- Forum: SD Mailing List Archive
- Topic: QUERY Structural changes and validity
- Replies: 17
- Views: 12583
QUERY Structural changes and validity
Posted by ""Jack Homer"" <jhomer@comcast.net> John Gunkler writes: >I wish there were a better way in SD modeling to show how one policy (rate >equation) can become a different one. We could then have models that >adapted to, or learned from, their environments. While I can think...
- Tue Sep 18, 2007 2:17 pm
- Forum: SD Mailing List Archive
- Topic: QUERY "Flawless Consulting" and SD
- Replies: 17
- Views: 12700
QUERY ""Flawless Consulting"" and SD
Posted by ""Jack Homer"" <jhomer@comcast.net> Kim Warren writes: > I can't speak for how consultants in general approach the challenge of > embarking on data collection, but have come across everything from [a] > ""give us everything you have got, and we will see what i...
- Sat Sep 01, 2007 12:05 pm
- Forum: SD Mailing List Archive
- Topic: QUERY Getting a Good Problem Statement
- Replies: 36
- Views: 24219
QUERY Getting a Good Problem Statement (SD6528)
Posted by ""Jack Homer"" <jhomer@comcast.net> Richard Stevenson writes (SD6544): ""In a sense, this process summarises a paradox and an implicit problem of SD - despite considerable achievements in education and academia, it just cannot make a significant impact in the ...
- Sun Apr 22, 2007 3:30 am
- Forum: SD Mailing List Archive
- Topic: QUERY Age of material in a stock
- Replies: 28
- Views: 26481
QUERY Age of material in a stock
Posted by ""Jack Homer"" <jhomer@comcast.net> Jay Forrester asks: ""Can someone supply some examples of where the way of computing age in a stock will alter the direction of policy recommendations to improve the behavior of a system?"" My doctoral thesis in 19...
- Wed Apr 18, 2007 1:26 pm
- Forum: SD Mailing List Archive
- Topic: QUERY Age of material in a stock
- Replies: 28
- Views: 26481
QUERY Age of material in a stock
Posted by ""Jack Homer"" <jhomer@comcast.net> Tom Fiddaman writes: ""If you play with this, you'll find the expected steady state response. Replacing stuff_in with a pulse, a ramp, and exponential growth is interesting. It becomes apparent that for particular inputs, it...
- Mon Apr 16, 2007 1:13 pm
- Forum: SD Mailing List Archive
- Topic: QUERY Age of material in a stock
- Replies: 28
- Views: 26481
QUERY Age of material in a stock
Posted by ""Jack Homer"" <jhomer@comcast.net> Calculating average age of material in a stock is a special case of calculating any average attribute of a stock, for which the solution is a co-flow structure. See Sterman, Business Dynamics, Chapter 12. The incoming attribute in thi...
- Tue Apr 10, 2007 12:04 pm
- Forum: SD Mailing List Archive
- Topic: QUERY Student workload management
- Replies: 3
- Views: 3799
QUERY Student workload management
Posted by ""Jack Homer"" <jhomer@comcast.net> There is a long history of SD modeling applications to questions of workload management for students and workers of all types. In addition to what you will find in the SD Bibliography under worker burnout and also under service qualit...
- Wed Jan 10, 2007 12:39 pm
- Forum: SD Mailing List Archive
- Topic: QUERY SD Impact on National Government Policies
- Replies: 66
- Views: 61572
QUERY SD Impact on National Government Policies
Posted by ""Jack Homer"" <jhomer@comcast.net> The idea that the field has been growing at a rate of 10-20% per year sounded like an old estimate to me, so I decided to look at some actual data. Thanks to Roberta Spencer for the raw data; any errors in calculation of average growt...