When to Use Paper - Paper Prototyping: The Fast and Easy Way to Define and Refine User Interfaces - page 250

Development
context

The interface is a
standalone piece of
software or other
technology.

There are many software
modules required for
successful completion of the
tasks.

All the software modules
needed for usability testing
are stable, or we're
confident we can test
around the problems
without too much difficulty.

Some software modules are
under development, are of
uncertain reliability, or
otherwise not under our direct
control.

People are constantly
submitting changes—we either
have to ask them to hold off for
a few days or we'd need to set
up a separate test environment.

It's not a problem to pause
development for a couple
of days to do usability
testing.

It's not difficult to set up a
test environment, including
hardware, databases,
accounts, etc.

It would take time and/or
money to set up a test
environment, or it would be
hard to create one that's
sufficiently realistic.

We can control everything
the user sees, including
product databases and
ads.

Some of the content comes
from sponsors, manufacturers,
or other outside sources, and
we can't always predict or
control it.

Tasks, data,
and test
scenarios

Reset procedures are
minimal—transactions can
be easily faked or
reversed.

Resetting the test environment
between tests is
complicated—transactions are
real, high consequence, or
difficult to undo.

Installation and
configuration are not being
tested.

Tasks include installation or
configuration.

There are no long delays
for the user to sit
through—a minute at
most, and usually less.

The user may have to wait
more than a minute or two for
the system to do its processing.

The set of tasks is known in
advance; we've created them. We want users to bring

their own real tasks to the
test session.

Timing and
scope

Usability testing can wait
until the middle or end of
the development process.

Usability testing before or
during development is
desirable.

There is a previous
working version of the
interface.

The interface doesn't exist yet
or needs to be substantially
redesigned.

We can't make huge
changes at this point, just
a few tweaks.

We know there are significant
problems, or we'd like to
experiment with solutions.