Subject: Glossary

Posted by Richard Turnock on 2/3/2010
In Reply To:Systems Languagg Posted by Tim Joy on 2/3/2010

Message:

Road Maps Glossary
http://sysdyn.clexchange.org/sdep/Roadmaps/RMGlossary/D-4498.pdf

accumulation: The collection of some quantity over time. Examples of accumulation
include water in a bathtub, savings in a bank account, inventory. In the STELLA
modeling software, the accumulator is also referred to as a Stock or Level.

integration: See accumulation, stock, level

level: An accumulation in a system. It represents the accumulated difference between
inflow and outflow rates, illustrating the results of action within the system over
time. Levels are conserved

reservoir: The type of stock that is analogous to a tub with water flowing in and draining
out. In many ways it is the simplest of stocks. When something flows into a tub,
it is mixed into any "stuff" that is already in the tub so that it can not be
distinguished from earlier or later inflows.

state variable: See stock, level

stock: An element of a system that is accumulating or draining over time. Stocks are the
memory of a system and are only affected by flows. Also known as levels, they
are signified by rectangles in system dynamics diagrams.

Follow Ups:

Glossary - Tim Joy 2/3/2010 
Glossary - Bob Gorman 2/3/2010
Glossary - Ed Johnson 2/3/2010
Systems Language - Tim Joy 2/4/2010