SD knowledge/Text Based Models
Posted: Wed Apr 18, 2001 9:23 am
Folks,
Some of you will have noticed concerns Ive expressed in the past months about erroneous models, that is to say, models in which the equations are technically incorrect or which calculate incorrectly for a number of other reasons. Last week, I mentioned rate-dependent-rates and Ive now received the following query. I quote it verbatim as nothing in it identifies its author, other than to himself.
Would you elaborate on rate-dependent-rates? I think myself and other
people new to SD dont know the definition. Thanks.
I can only say that this worries me deeply. When I was a newcomer to SD, more than 30 years ago, I read a textbook (Forresters masterpiece) and went to lectures to find out about this new subject. I did the same when I learned about calculus (that was at school, with a most gifted maths master, Mr Whitehead (aka Sir), long since dead but still honoured in my mind and acknowledged in one of my books). I did the same when I learned about linear programming and so on. I dont want to be rude to this enquirer but it amazes me that someone new to a subject should try to pick it up by such casual enquiry and should expect me to devote time to writing notes about this topic, and many others in SD, one of which is the correct use of DT.
Rate-dependent-rates are specifically mentioned in the following textbooks: Forrester, 1961; Coyle 1977, 1966 (which has much more on correct modelling techniques, as does my Equations for Systems), Richardson and Pugh, 1981; Wolstenholme 1990. I could not find it in the index of Sterman 2000, but Im sure its there somewhere.
I can only urge newcomers to SD to study the subject properly, rather than trying to pick it up from half-reading a software manual. Excellent though those are, their purpose is to explain the use of software, not to teach SD. Maybe the Society needs to think again about its training and educational needs because, as this enquiry might be paraphrased other people new to SD dont know much about it.
Geoff Coyle
From: "geoff coyle" <geoff.coyle@btinternet.com>
Some of you will have noticed concerns Ive expressed in the past months about erroneous models, that is to say, models in which the equations are technically incorrect or which calculate incorrectly for a number of other reasons. Last week, I mentioned rate-dependent-rates and Ive now received the following query. I quote it verbatim as nothing in it identifies its author, other than to himself.
Would you elaborate on rate-dependent-rates? I think myself and other
people new to SD dont know the definition. Thanks.
I can only say that this worries me deeply. When I was a newcomer to SD, more than 30 years ago, I read a textbook (Forresters masterpiece) and went to lectures to find out about this new subject. I did the same when I learned about calculus (that was at school, with a most gifted maths master, Mr Whitehead (aka Sir), long since dead but still honoured in my mind and acknowledged in one of my books). I did the same when I learned about linear programming and so on. I dont want to be rude to this enquirer but it amazes me that someone new to a subject should try to pick it up by such casual enquiry and should expect me to devote time to writing notes about this topic, and many others in SD, one of which is the correct use of DT.
Rate-dependent-rates are specifically mentioned in the following textbooks: Forrester, 1961; Coyle 1977, 1966 (which has much more on correct modelling techniques, as does my Equations for Systems), Richardson and Pugh, 1981; Wolstenholme 1990. I could not find it in the index of Sterman 2000, but Im sure its there somewhere.
I can only urge newcomers to SD to study the subject properly, rather than trying to pick it up from half-reading a software manual. Excellent though those are, their purpose is to explain the use of software, not to teach SD. Maybe the Society needs to think again about its training and educational needs because, as this enquiry might be paraphrased other people new to SD dont know much about it.
Geoff Coyle
From: "geoff coyle" <geoff.coyle@btinternet.com>