visualizing systems

© Tim Sheiner, all rights reserved

Visualizing SystemsAn overview of the options


A system is an interconnected set of elements that is coherently organized in a way that achieves something.

Donella Meadows, Thinking in Systems


Show me a picture


Concept Structure

Dynamics

Behavior


Visualizing System Behavior


Graphs๏ Most standardized system visual

➡ Used to present recorded data ➡ Taught in schools, used (and abused) by large number of disciplines➡ Lots of software tools available for drawing these

๏ Several roughly synonymous names➡ graph➡ chart➡ plot

๏ Abstracted, non-representational view➡ Many types: line, bar, dot, spider, etc.➡ All based on cartesian system (x vs y)


Line Graph Conventions

0

y (u

nits

)

5

7Origin x (units)

dependent variable

independent variable

Plot of y=x title

axis

axis


Complex Example

key

2 y-axes

This is actually 3 graphs displayed on top of each other: 2 line charts and 1 bar chart


Independent Variable not always Time

In drug development an important relationship is the response (dependent variable) or outcome that occurs for a given dose (independent variable) of a drug

Dose vs Response


Simple plots are never “true”

recorded value

uncertainty

best “fit” This graph actually displays a great deal of qualifying information


System response is probabilistic

% Inhibition

40

50

30

Probable Response at Dose log10-4 Progesterone (M)


Visualizing System Dynamics


Flow Diagrams๏ Represent system dynamics in a static form๏ Some standardized conventions

➡ standard generic flow chart conventions➡ detailed standards for engineering flow disciplines like electronics➡ attempts at standardization for systems theory

๏ Range from representational to schematic


Generic Flow Chart ConventionsStart

Process Step 1

DecisionNo

A

Yes

Process Step 2

A

Process Step 2

End

“I’ve run out of space, find a similar symbol elsewhere in drawing to continue flow”


Example of Electronics Conventions


Heating Dynamics Representationally

Heat

Signal

Decision


Heating Dynamics as Stocks & Flows

An existing standard for representing flow in classical system thinking literature.

Difficult to parse?


Heating Dynamics as Flow Schematic

Alternative representation of thermostat system by Dubberly & Pangaro.

Cold air outside

is m

easu

red

by

can increase

input

output

Bi-metal coil Heater

System

Desired temperature e.g. 68º

air temperature in the room

low

ers

the

. . . is indicated by adjusting the temperature control lever which in turn moves the bi-metal coil; increasing the desired temperature moves the coil closer to the contact point; decreasing the desired temperature moves the coil further from the contact point

Why does a bi-metal coil bend? bi-metal coils consist of two layers of metal (usually iron and copper) joined together to form one flat strip; because the metals have different coefficients of expansion, the strip will bend in one direction as it cools, and the opposite direction as it warms

Contact point . . .bends to touch the. . . . (as it cools)

external electrical source

. . .bends the opposite direction to lose contact with the. . . (as it warms)

. . . . which sends a signal to the. . .

. . . . thus no signal is sent, and the heater shuts off

. . . sends current to. . .

41January 2010 | Developed by Paul Pangaro and Dubberly Design Office

Feedback: Classic ExampleThermostat regulating room temperature (via a heater)


System

Goal

Environment

Disturbances

a Comparator

is embodied in

subtractsthe current state value

fromthe desired state value

to determinethe error

is m

easu

red

by affects the

. . . describes a relationship that a system desires to have with its environment

. . . may be characterized as certain types typically falling within a known range; but previously unseen types may emerge and values may vary beyond a known range; in such cases the system will fail because it does not have requisite variety

. . . has resolution – (Accuracy) frequency – (Latency) range – (Capacity)

. . . has resolution frequency range

can

affe

ct th

e

input

output

a Sensor passes the current state value to . . . . . . . . . . responds by driving an Actuator

39January 2010 | Developed by Paul Pangaro and Dubberly Design Office

Feedback: Formal Mechanism

Generic Flow Schematic

Combines flow and concept map conventions and is reasonably easy to ‘read.’

A better standard for systems flow visualizations?


Visualizing System Structure


Illustrations๏ Used to explain behavior or method of construction๏ Very standardized in some contexts

➡ Mechanical Engineering➡ Architecture

๏ Must be representational to be useful➡ Representation challenging for abstract systems➡ With abstract systems, illustrations of structure and flow diagrams

hard to distinguish from one another


Standardized in Physical Disciplines


Some Abstract Standardizations Exist

UML is an example of a standard for abstract systems that has some degree of penetration among object oriented programmers and system architects.


Ad Hoc Structure for Abstract Systems

Current state of the art for illustrating the structure of an abstract system involves simple symbols, shapes, arrows & annotation


Visualizing System Concepts


Concept Maps๏ Used to communicate mental models๏ Present ideas and relationships

➡ Rely on text not symbols➡ Use arrows to communicate relationships not flow

๏ Not at all representational


Concept Map Conventions

redrawn from http://redie.uabc.mx/contenido//vol2no1/art-11-eng/contenido-ruiz-figura1.png

is a

Concept Map

graph

nodes concepts

with

representing

linking lines

with

linking wordsthat have

relating that explain the

relationships between


Concept Map Examples


Animating System Visuals


Animated System Visualizations๏ Static pictures are inherently limited in their ability to

explain dynamic systems๏ Animated presentations can provide a richer

communication experience➡ can use audio➡ can use time➡ can use feedback

๏ Animated presentations are systems in themselves➡ computer simulations➡ keyframes animations & videos➡ prototypes➡ new forms of content


System Simulations

Most system simulation tools are too complex and proprietary for common use, but simpler, web-based tools are being developed.


Keyframe Animations & Video

Click-thru mockups are a powerful form a system visualization.

They can be converted to videos to simulate the experience of interacting with the system.


Interactive Prototype

An interactive prototype is a tool for creating a mental model in a person’s mind of a system that does not yet exist.


New forms of content

Documents combining interactivity, words and sounds may eventually become a common way to explain systems.

Watch: http://www.ted.com/talks/mike_matas.html

http://www.ted.com/talks/mike_matas.html

http://www.ted.com/talks/mike_matas.html


System Visualization Conclusions๏ Static pictures of systems are compact and portable๏ The right picture to produce depends upon what

aspect of a system you want to communicate or understand➡ Behavior = Graphs➡ Dynamics = Flow Diagrams➡ Structure = Illustrations➡ Concepts = Concept Maps

๏ Animated system visualizations convey more information than static presentations and may ultimately become the standard for describing systems