8 Characteristics of good user requirements

The 8 caracteristics can be used as "filters" when producing good user requirements.

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The 8 Characteristics
of a good user
requirements
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2. 2
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What Are the 8 Characteristics of Good
User Requirements?
Think of these Think of these
characteristics as a characteristics as a
series of filters. A series of filters. A
good requirement good requirement
will pass through will pass through
all eight filters.all eight filters.
A user requirement is good
if it is:
1.Verifiable
2.Clear and concise
3.Complete
4.Consistent
5.Traceable
6.Viable
7.Necessary
8.Implementation free

3. 3
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What Makes a UR Verifiable?
A verifiable requirement …
•is stated in such a way that it can be tested by:
- inspection,
- analysis, or
- demonstration.
•makes it possible to evaluate whether the system
met the requirement, and
•is verifiable by means that will not contaminate
the product or compromise the data integrity.

4. 4
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Is this Is this UR Verifiable? Verifiable?
•Good example:Good example:
-UR1: The user UR1: The user
interface shall be interface shall be
menu driven. It shall menu driven. It shall
provide dialog provide dialog
boxes, help screens, boxes, help screens,
radio buttons, radio buttons,
dropdown list boxes, dropdown list boxes,
and spin buttons for and spin buttons for
user inputs.user inputs.
•Bad example:Bad example:
-UR1: The system UR1: The system
must be user friendly.must be user friendly.
-How should we How should we
measure user measure user
friendliness?friendliness?

5. 5
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What Makes a UR Clear & Concise?
A clear & concise requirement …
•must consist of a single requirement,
•should be no more than 30-50 words in length,
•must be easily read and understood by non
technical people,
•must be unambiguous and not susceptible to
multiple interpretations,
•must not contain definitions, descriptions of its use,
or reasons for its need, and
•must avoid subjective or open-ended terms.

6. 6
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Is this UR Clear & Concise?
•Good example:Good example:
-UR2: When the UR2: When the
user accesses user accesses
any screen, it any screen, it
must appear on must appear on
the monitor the monitor
within 2 within 2
seconds.seconds.
•Bad example:Bad example:
-UR2: All screens UR2: All screens
must appear on must appear on
the monitor the monitor
quickly.quickly.
-How long is How long is
quickly?quickly?

7. 7
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What Makes a UR Complete?
A complete requirement …
•contains all the information that is needed to
define the system function,
•leaves no one guessing (For how long?, 50 % of
what?), and
•includes measurement units (inches or
centimeters?).

8. 8
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Is this UR Complete?
•Good example:Good example:
-UR3: On loss of UR3: On loss of
power, the power, the
battery backup battery backup
must support must support
normal normal
operations for operations for
20 minutes.20 minutes.
•Bad example:Bad example:
-UR3: On loss of UR3: On loss of
power, the power, the
battery backup battery backup
must support must support
normal normal
operations.operations.
-For how long?For how long?

9. 9
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What Makes a UR Consistent?
A consistent requirement …
•does not conflict with other requirements in the
requirement specification,
•uses the same terminology throughout the
requirement specification, and
•does not duplicate other URs or pieces of other
URs or create redundancy in any way.

10. 10
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Is this UR Consistent?
•Good example:
-UR4: The electronic
batch records shall
be 21 CFR Part 11
compliant.
-UR47: An on-going
training program for
21 CFR Part 11
needs to be
established at the
site.
•Bad example:
-UR4: The electronic
batch records shall be
Part 11 compliant.
-UR47: An on-going
training program for
21 CFR Part 11 needs
to be established at
the sites.
-Do these refer to the
same regulation or
different ones?

11. 11
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What Makes a UR Traceable?
A traceable requirement …
•has a unique identity or number,
•cannot be separated or broken into smaller
requirements,
•can easily be traced through to specification,
design, and testing.
•Change Control on UR level.

12. 12
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Is this UR Traceable?
•Good example:Good example:
-UR6UR6v1v1: The system must : The system must
generate a batch end generate a batch end
report when a batch is report when a batch is
aborted.aborted.
-UR7UR7v2v2: The system must : The system must
generate a discrepancy generate a discrepancy
report when a batch is report when a batch is
completed or aborted.completed or aborted.
•Bad example:Bad example:
-UR: The system must UR: The system must
generate a batch end report generate a batch end report
and a discrepancy report and a discrepancy report
when a batch is aborted.when a batch is aborted.
-How is this uniquely How is this uniquely
identified? If the identified? If the
requirement is changed requirement is changed
later so that it does not later so that it does not
require a discrepancy require a discrepancy
report, how will you trace it report, how will you trace it
back so you can delete it? back so you can delete it?

13. 13
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What Makes a UR Viable?
A viable requirement …
•can be met using existing technology,
•can be achieved within the budget,
•can be met within the schedule,
•is something the organization has the necessary
skills to utilize,
•will be used by the end users, and
•must be helpful to build the system.

14. 14
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Is this UR Viable or Feasible?
•Good example:Good example:
-The replacement The replacement
control system control system
shall be installed shall be installed
causing no more causing no more
than 2 days of than 2 days of
production production
disruption.disruption.
•Bad example:Bad example:
-The replacement The replacement
control system shall control system shall
be installed with no be installed with no
disruption to disruption to
production.production.
-This is an unrealistic This is an unrealistic
expectation.expectation.

15. 15
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What Makes a UR Necessary?
A necessary requirement …
•is one that must be present to meet system
objectives, and
•is absolutely critical for the operation of the
system,
•leads to a deficiency in the system if it is removed.

16. 16
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Is this UR Necessary?
•Good example:Good example:
-The desktop PCs for The desktop PCs for
the developers on the the developers on the
project must be project must be
configured with 512MB configured with 512MB
of memory, DVD ROM/of memory, DVD ROM/
CD-RW multifunction CD-RW multifunction
drive and a 21-inch flat drive and a 21-inch flat
screen monitor.screen monitor.
•Bad example:Bad example:
-All desktop PCs for the All desktop PCs for the
project must be project must be
configured with 512MB of configured with 512MB of
memory, DVD ROM/CD-memory, DVD ROM/CD-
RW multifunction drive RW multifunction drive
and a 21-inch flat screen and a 21-inch flat screen
monitor.monitor.
-This may not be needed This may not be needed
for all PCs for the project.for all PCs for the project.

17. 17
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What Makes a UR Free of Implementation
Details?
A requirement that is free of implementation
details …
•defines what functions are provided by the
system,
•does NOT specify how a function can or should be
implemented, and
•allows the system developer to decide what
technology is best suited to achieve the function.

18. 18
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Is this UR Free of Implementation Details?
•Good example:Good example:
-After 3 unsuccessful After 3 unsuccessful
attempts to log on, the attempts to log on, the
user must be locked user must be locked
out of the system.out of the system.
•Bad example:Bad example:
-After 3 unsuccessful After 3 unsuccessful
attempts to log on, a Java attempts to log on, a Java
Script routine must run Script routine must run
and lock the user out of and lock the user out of
the system.the system.
-Specifying a JavaScript Specifying a JavaScript
routine concerns how the routine concerns how the
requirement will be requirement will be
implemented.implemented.