Both STELLA and iThink allow you to quickly create system diagrams that can be simulated over time. Working in a completely risk-free environment,
you can test hypotheses and policy interventions repeatedly until you achieve the outcomes desired. Discover hidden aspects of your system that
lead to unexpected outcomes. STELLA and iThink also allow you to create a user interface on top of your system diagram that makes it easy to
share your understanding of the system, run your scenarios as part of a presentation, and enable others to experiment with their own policy combinations.
STELLA is the leading systems modeling tool for education and research, used at all educational levels to stimulate learning for subjects such as
economics, physics, literature, calculus, chemistry, and public policy. STELLA models allow you to communicate how a system works – what goes
into the system, how those inputs impact the system, and what are the outcomes.
iThink is more commonly used for business applications, e.g., to simulate and improve business processes, understand the working of your business
more holistically, and develop new and exciting business strategies. iThink includes strong communication features to share the interdependencies
between processes and problems within your business, and to safely explore potential improvements.
Dynamically explore model behavior using Stella Live™. On the Interface Layer, change any constants in the model by dialing
them up or down and immediately see the results for all objects displayed directly on the diagram
Time stamp and track material as it flows through the model in order to precisely compute
how long different tasks and activities are taking
Mark a Converter as changing over time in response to changes in its input as happens
with SMTH1, SMTH3, DELAY, DELAY3 and related Builtins
Graphs can now take user input: you can create a sketch of the expected behavior of a model
variable over time. When the simulation is run, you will be able to compare your sketch to the
actual behavior of the variable. Sketchable graphs come in handy when you want users of your
model to "put a stake in the ground" regarding the performance of the model. Discrepancies
between expected and actual performance can motivate effective, efficient learning experiences.
It is now possible to turn off shading for interface controls giving a cleaner more modern appearance
to interfaces - supported on both the Desktop and Netsim. Use the Interface preferences dialog to change this.
Tables now store information about reporting period and type of reporting individually so you
can have different tables with different settings. Rerunning the model is no longer necessary
when changing the report interval and other reporting options.
CTFLOW, CTMEAN, CTMIN provides more robust streams of values for the different random number Builtins.
CTSTDDEV, CYCLETIME, THROUGHPUT as well as UNIFORM for random number generation and GAMMALN for statistical computations
Whatever runs are held by the data manager will immediately be displayed in
comparatives when you specify the variable
Keep your model files organized. Module files are stored in a folder prefixed with the model name so that you can save
a separate copy of a model using modules in file, without changing the original model
A. From a functional perspective, the STELLA and iThink programs are virtually
identical. Each is designed to facilitate the mapping, modeling, simulation, and
communication of dynamic processes.
The major difference between the two products is in their target markets and the
corresponding Introduction to Systems Thinking books. STELLA is targeted toward
individuals in educational and research settings. The Introduction to Systems
Thinking for STELLA covers the natural and social sciences. Applications and
sample models demonstrate how the software can be applied in Biology,
Chemistry, Environmental Science, Economics, Psychology, History and Physics.
iThink, on the other hand, is targeted toward an audience of users in business
settings. The Introduction to Systems Thinking for iThink is written with the
business user in mind. Applications and sample models cover the gamut of
business uses including Business Process Re-engineering, Strategic Planning,
Financial Analysis, Manufacturing, Operations Research, Forecasting, and
In deciding between STELLA and iThink, simply match the appropriate product to
your own needs. If you're in an educational or scientific research setting, STELLA
is the best match. If you're working with business-oriented issues, iThink is the
Stella Professional is intended for all users regardless of the nature of their work.
A. Yes, whether you are using STELLA or iThink you can open both STELLA models
(.stmx and .stm files) and iThink models (.itmx and .itm files).
Stella Professional is designed to be compatible with, and can open,
STELLA/iThink version 10.1 models (.stmx and .timx). Model files created by
earlier versions of STELLA/iThink are not guaranteed to open correctly in Stella
A. Version 10.1 supports the use of models created in Stella Professional and maintains model elements
that have been customized in Stella Professional (such as fonts, sizes, and specialized
layout with bezier curves). This allows you to do model development work in Stella Professional
and Interface development work in Version 10.1.
A. If you are using a Windows computer you can open and run models that were
saved on a Macintosh. You do not need to convert the models.
If you are using a Macintosh computer and are running version 9 or later, you can
open and run models that were saved on a Windows PC. You do not need to
convert the models.
A. Yes, models can be shared between Stella Professional 1.0 and STELLA/iThink 10.1. Models created and
saved in versions of STELLA/iThink before version 10.1 cannot be used in Stella Professional with reliability.
Likewise, Stella Professional models cannot be used win STELLA/iThink versions earlier than 10.1.
A. STELLA, iThink, and Stella Professional are available in both Windows and
Macintosh versions. Below are the minimum system requirements depending on
the operating system of your computer.
A. Yes, STELLA and iThink will run on 64-bit Windows 7/8 machines with
compatibility properties set as shown here.
(Stella Professional does not require special settings in compatibility properties.)
A. Yes, version 10 and later of STELLA and iThink supports Mac OS X 10.7 (Lion) and
10.8 (Mountain Lion). Stella Professional requires at least Mac OS X 10.9 (Mavericks).
A. Opening a STELLA or iThink model that was created in a previous version will
automatically translate the model so that it is compatible with version 10. Click
here for details about how the software handles specific translation issues.
A. STELLA and iThink models can easily be published to the web using the isee
NetSim add-on utility. isee NetSim allows anyone with a web browser the ability
to interact with and run your simulations on the web. For more information about
isee NetSim, Click Here
Another option for running your simulations on the Web is to create a custom Web
interface and extend your model using the isee.NET Framework Software
Development Kit (SDK). For more information about isee.NET Framework, Click Here
A. If you want to link data to your model, you can set up dynamic data
import/export links to Microsoft Excel. If you want to integrate your model with
other applications or databases you can use the isee.NET Framework SDK to
programmatically access the interface objects in your model.
For detailed help information about isee.NET Framework, Click Here
A. Drop a Flow and start dragging it. When you want it to change direction at a 90
degree angle, hold the shift key while you move the cursor in the direction you
want the Flow to go. For more tips and tricks about using STELLA and iThink, read
our blog post.
A. To set the precision level for multiple variables in a Table, right click on the
variable names in the Table that you want to change. Once you have selected all
of the variables, double-click on the name of one of the selected variable to open
the Format Variable Table dialog. For more tips and tricks about using STELLA and
iThink, read our blog post.
A. To delete a page on a Graph or Table Pad in STELLA/iThink v10, click the page-
turn button in the lower left hand corner of the Graph or Table Pad until the page
that you want to delete is showing. Next, click on the button on the toolbar to
select the Dynamite tool. Using the Dynamite tool, click on the page-turn button
again and the page showing will be deleted. For more tips and tricks about using
STELLA and iThink, read our blog post.
To delete a page in Stella Professional, select the table and open the properties
panel. Use the Green Plus button to add pages and the Red Minus button to remove pages.
A. A Module is a container for lower-level model structure. It is designed to support a
process of top-down model design and development. For more information and
frequently asked questions about Modules, read our blog post.
A. If you have Connectors into a Module that are not being used or there are inputs
inside the Module that have not been assigned, the Module will not run in an
upper level of the model hierarchy.
A. For STELLA and iThink: Click Here
For Stella Professional: Click Here
A. It may be a missing picture, Excel spreadsheet or some other imported file. When
copying a model from one computer to another, you may need to copy more than
just the model file. If your model uses other files such as graphics, sounds or
spreadsheets you’ll need to package all of them with the model file. For more
details, read our blog post.
A. Yes, you can open and run a STELLA/iThink model from a Windows command line.
You can also perform a host of other operations using the command line. For
more details, read our blog post.
A. Spatial Map is a stand-alone application that allows you to map array data in your
model to color values or images so that you can view your data as three-
dimensional, spatial information. In the spatial map, the x and y axes are defined
by the bounds of the array and z is represented by a color or image. (Elevation
and temperature are examples of z values.) To see an example, read our blog post.
A. Yes, STELLA and iThink support matrix operations such as addition, subtraction,
transposition, multiplication and division. For more details, read our blog post.
Additional information for version 10 and later can be found here.
A. Yes, you can build causal loop diagrams in STELLA and iThink using modules or delay converters. You
can also link a CLD to a working stock and flow model. To learn more and see an
example, read our Blog Post.
A. Storytelling is a feature unique to STELLA and iThink that allows you to present
and explain your model piece-by-piece. Even more powerful, however, is the
ability to show the behavior as the structure of the model unfurls. Through
storytelling, you can clearly create and communicate the link between the
structure of the system and the dynamic behavior. For more details, read our blog post.
A. Most likely, this is a permissions issue. To fix this problem, follow these steps:
A. Copy and then Paste into Word, PowerPoint, or Illustrator. For the highest quality, you must hold down the SHIFT key for
the duration of the Copy command. I.e., either hold down Shift-Ctrl-C or hold down Shift and while it's down, select
Edit->Copy, then let go of Shift. Note that on Windows, Quicktime for Windows also needs to be installed. That allows Word,
PowerPoint, and Illustrator to understand the PCT format.