Summary: Putting It All Together - Foundations for Designing User-Centered Systems - page 390

General/
DoD Milestones

OCR 1 /C 1
DCR 2 /B 2

OCR 2 /C 2
DCR 3 /B 3

ECR VCR/CD ACR/A DCR/B

ICM
Life-cycle Phases

Activities

E
Simple Enterprise

A

High, but
addressable

Acceptable Acceptab le Accepta ble Accepta ble ...

R
based application

e P (

Risk? Risk? Risk? Risk? Risk?

Too high,
unaddressable

Negligible Negligible

Example B.
Complex, but feasible
product development

Accepta ble Accepta ble Acceptab le Accepta ble Accepta ble ...

Risk? Risk? Risk? Risk? Risk?

Example C.
Stakeholders agree that

Accepta ble Accepta ble Acceptab le Accepta ble Accepta ble ...

more convergence of

objectives is necessary

Risk? R isk? Risk? Risk? Risk?

High, but
addressable

Accepta ble

Accepta ble

Example D.
A superior product
enters the market

Risk? Risk? Risk? Risk? Risk?

Too high,
unaddressable

Discontinue

Fig. 14.5 The RD-ICM laid out linearly. This figure also shows the role of risk in system
development, showing how different risk patterns yield different processes. Reprinted from Pew
and Mavor ( 2007 ) with permission from the National Academy of Sciences, courtesy of the
National Academies Press

Pew and Mavor ( 2007 , pp. 91-133) provide three examples of using the Risk-
Driven Spiral Model method to develop specific systems. These examples are
taken from different domains and are different sizes. Their Chap. 5 ( http://www.
nap.edu/openbook.php?record_id=11893&page=91 ) covers the development
of an unmanned aerial system (i.e., an unmanned aerial vehicle, a UAV) for the
military, a port security screening system for homeland security, and an intrave-
nous infusion pump for use in hospitals. Each example covers different aspects of
the process, so together they provide fairly broad coverage of the approach.
The model is relatively complex, so we advocate that another way to under-
stand it is through the viewpoint of concurrent activities. The standard way of
presenting the model is as a spiral (as shown in Fig. 14.4 ), although the spiral can
be unwound and the task activity levels can be represented in a linear fashion
(Fig. 14.5 ), which makes it easier to recognize the concurrent phases of devel-
opment, as well as concurrent activities that are out of phase and aspects like
stakeholder commitment review points where the risks are assessed.