Value Based Requirements Engineering
And Prioritization
Percolating ‘Value’ into the SDLC
(Software Development Lifecycle)
Nupul Kukreja
2nd October, 2013
1
Insightful Questions
• Given N requirements and budget/schedule
constraints which ones to implement?
• Which test cases should I run given time
constraints?
• What programming language should I choose?
• Which design should I choose?
• What framework should I choose?
• What architecture should I choose?
• Which project(s) should we choose?
• Heck! How do I choose anything?
3
Agenda
• The ‘science’ of decision making – what, why
and how?
• The role of decision making in Value Based
Requirements Engineering & Prioritization
(VBRE/RP)
• Importance of ‘Planning’
• VBRP – what, why & how?
• Understanding VBRP in CS577
• VBRP in Action
4
Agenda: VBSE 4+1 View
5a, 7b. Options, solution
development & analysis
Dependency
Theory
2a. Results chains
2. Identify SCS
3b, 5a, 7b. Cost/schedule/
performance tradeoffs
3b, 7a. Solution Analysis
6, 7c. Refine, execute,
monitor & control plans
Control
Theory
6a, 7c. State measurement,
prediction correction;
Milestone synchronization
3. SCS Value
Propositions
(Win Conditions)
Theory-W:
SCS Win-Win
1. Protagonist goals
3a. Solution Exploration
7. Risk, opportunity,
change management
Utility
Theory
4. SCS expectations
management
5a, 7b. Prototyping
5. SCS WinWin
Negotiation
Decision
Theory
5a. Investment
analysis, Risk analysis
5
Decision Making – What?
Definition:*
• Decision making can be regarded as the
mental processes (cognitive process) resulting
in the selection of a course of action among
several alternative scenarios
• Every decision making process produces a
final choice
• The output can be an action or an opinion of
choice.
*Courtesy: http://en.wikipedia.org/wiki/Decision_making
6
Decision Making – Making a Choice
Which apartment do you want to live in?
7
Making a Choice – How?
• So, just how did you choose your apartment?
• What all did you ‘see’ / evaluate before
signing the lease?
• Examples of possible criteria:
– Rent per month
– Location i.e., quality of area
– Proximity to campus
– Presence of a good looking neighbor 
– …and probably several others
8
Analyzing the ‘Problem’
• You have the two key ingredients necessary for a
decision problem:
– A list of criteria
– A set of alternatives
• Problem: Given a list of criteria AND a set of
alternatives select the alternative that best suits the
given criteria
Criteria
Decision
Apartment
Analysis
Selection
Alternatives
Rank ordered set of alternatives
apartments
9
Decision Making – Why Bother?
• Converts ‘art’ into science
– Adds rigor to the act of decision making
• Justification of choice of action i.e., why you
chose what you chose?
– Helps decrease legal liability
Ex.: Why did Company A select the bid/tender of
Company X over Y? (It’s not only cost )
• Documents the institutional memory that lead
to that particular decision (i.e., helps trace
back to provide justification of decision)
10
Decision Making – How do you do it?
• If it is a well studied science (it is) does anything
exist ‘out there’ to help practice this ‘science’?
• There are various techniques that can be
employed:
–
–
–
–
Multi-attribute utility theory (ISE 562 in Fall)
Analytical Hierarchy Process (AHP)
Simple Additive Weighting (SAW)
TOPSIS (Technique of Ordered Preference by Similarity
to Ideal Solution)
– …and many more (http://en.wikipedia.org/wiki/MCDA#MCDM_Methods)
11
Decision Problem – Look and Feel
Almost always has a matrix-like representation:
Criterion
1
Criterion
2
Criterion
3
…
Criterion
N
Alternative 1
S
S
S
S
When
considering
multiple
criteria…in decision
Alternative
S is often
S
…
making2 theSproblem
referred
toS as
“Multiple
Decision
Analysis”
or
Alternative 3 Criteria
S
S
S
… (MCDA)
S
“Multiple
Criteria
Decision
Making”
(MCDM)
…
…
…
…
…
…
Alternative N
11
12
13
1N
21
22
23
2N
31
32
33
3N
SN1
SN2
SN3
…
SNN
Sij = Measure of how well Alternative ‘i‘ does on Criterion ‘j’
12
Okay, Great! But what has any of it got
to do with VBSE?
• Everything!! 
Control
Theory
• How do you decide:
Which requirement to implement first?
Which component to design first?
Which architectural style/pattern to use?
Which requirements to test first?
Which test-cases form part of the regression
suite?
What all to prototype first?
For which component to write the “first line of
code”?
13
Wait! But I’ve already done all of this
before and I got it right too!
• Probably! However…
• Were you able to justify your choice i.e., how
you came about choosing a specific option?
– Was there ever a need to do so? 
• Just “how” did you decide?
– Perhaps intuition, gut feel, domain knowledge,
tossing a coin, do as the Romans do…
• Yes, a simple 1-10 works or even MoSCoW
(Must, Should, Could, Would – have) but for
relatively simple problems
14
Short Detour: Planning
15
Purpose of ‘Planning’*
• Why do we do it?
– Reduce risk & uncertainty
– Supporting better decision making
– Establishing trust (i.e. frequent delivery)
– Conveying expectations
• Planning is a ‘quest for value’
– Attempt to find an optimal solution of the overall
product development question:
What should be built?
*Agile Estimation & Planning – Mike Cohn
16
A Good Plan
• One that stakeholders find sufficiently reliable
• One that can be used as basis for decision
making
– Approximate time to market
– An idea of the set of features
• Made more precise as project moves on
• Is a ‘living’ artifact showing the current status
of the project to avoid last minute surprises
• Is planned around ‘value’
17
Planning for ‘Value’*
• Stakeholders needs must be understood
• Just delivering features is not important
– Necessary to balance scope, schedule, cost and value of
features comprising the release
• Various factors impacting prioritization
– Financial value of having the features
– Cost of development
– Amount/significance of new knowledge
• Product (what)
• Project (how)
– Reducing Risk (Business/Technical)
• Schedule
• Cost
• Functionality
*Agile Estimation & Planning – Mike Cohn
19
Decision Making and Planning for Value
• Decision analysis techniques can be ‘overloaded’
to perform requirements prioritization…
• …the rank-ordered output of decision making
techniques could also rank-order requirements!
• Requirements prioritized against the
goals/needs/values of the stakeholders
 VBRP
• The prioritized requirements form the basis of
the ‘plan’ – what is being delivered, for how
much and by when?
20
The ‘Dimensions’ of Value
• Value is a multi-dimensional quantity, a simple 1-10
may not cut it (too many ties – Must have, Must-must
haves, must-must-must haves etc.)
• Value lies in the eyes of the beholder
…and so does its dimensions! 
• Dimensions are ‘hidden’ within the ‘expected benefits’
of the various stakeholders
• The benefits serve as the goals/objectives/criteria on
which to prioritize the requirements
• Point to consider: Are all dimensions* equally
important?
(*dimensions = benefits = criteria = goals = objectives)
21
Prioritizing Criteria/Value Dimensions
• All criteria may NOT be equally important
• But just HOW do you prioritize the criteria
themselves?
– A simple 1-10 (Yes, it works )
– A highly involved process like multi-attribute
utility theory (MAUT) to get the utility functions
for each criteria which shows the risk attitude of
each criterion
– Or another interesting technique - Project Success
Sliders*
* Radical Project Management by Rob Thomsett
22
Project Success Sliders
25%
50%
75%
Success
Criteria
(defined at
start of
project)
Image: Radical Project Management by Rob Thomsett
23
Project Success Sliders
25
1
50
2
100
4
75
3
25
1
75
3
50
2
It’s ‘subjective’ but an
extremely effective tool to
understand the importance
of expectations and their
relative tradeoffs!
They can (and are)
interpreted on a relative scale
i.e., twice as important, half
as much etc.,
Image: Radical Project Management by Rob Thomsett
24
Putting It All Together
You have:
1.Relative ranking of all criteria
2.List of requirements (or win conditions)
What else do you need?
• Scores! How well each requirement/wincondition does on each criteria
You STILL need something else…
• The decision analysis ALGORITHM!
25
Decision Analysis Algorithm: Given a set of criteria with
possible weights and the measure of how the alternatives rank
on the respective criteria find an optimal alternative
Criteria
Overall
Score
Alternatives
S(A1)
Alternative 1
S(A2)
Alternative 2
S(A3)
Alternative 3
…
…
S(AN)
Alternative N
Criterion
1
Criterion
2
Criterion
3
…
Criterion
N
W1
W2
W3
…
WN
S11
S12
S13
…
S1N
The scale of the scores could be
S21
S22
S23
…
S2N
absolute, relative, 1-10 (Likert
S31
S32
S33
…
S3N
Scale),
Fibonacci...
…must… be consistent
across …
…
…
…
criterion column
SN1
SN2
SN3
…
SNN
26
Algorithms for Practicing VBRP
• There are various algorithms in literature to
choose from along with those from MCDA/M:
–
–
–
–
–
–
–
–
–
–
Kano Analysis
Planning Poker
100-point assignment technique
Simple Additive Weighting
Quality Function Deployment (House of Quality)
Cost of Delay
Weigers’ Prioritization
Theory-W (Business value vs. Technical Feasibility)
TOPSIS
…and quite a few more 
27
What are we using in CS577?
• TOPSIS: Technique of Ordered Preference by Similarity
to Ideal Solution (MCDM Technique)
• Integrated in Winbook for prioritizing MMFs and win
conditions
• We’ll be using Business Value, Technical Feasibility and
Relative Penalty as the criteria against which to rank
the requirements. You may add more (e.g., risk, cost,
effort, time – anything you deem appropriate!)
• MMFs Prioritized against stakeholders’ value
propositions/goals/objectives
• Success Sliders for prioritizing value propositions
28
TOPSIS Primer
Alternative 1
Ideal Alternative
(S’)
Criterion 1
Non-Ideal
Alternative (S*)
Alternative 2
Criterion 2
Aim: Rank order alternatives by their ‘closeness to ideal’ and ‘distance from non-ideal’
Criterion: Has ‘direction of preference’ i.e. more/less of the criterion is preferred
Ideal: Best score for each criterion Non-ideal: Worst score for each criterion
29
30
Decision Theory Demo
Which tablet should I buy?
http://pattaya.usc.edu:8080/Winbook/
projects/2013-USC-Tablets/wall
31
Refinements to TOPSIS/VBRP
• Prerequisite Handling (not yet integrated in
Winbook)
– Specifying MMF/WC prerequisites and factoring in
prioritization
– Simple solution: Priority of item less than all those
in its prerequisite graph
• Hierarchical Prioritization (partially integrated)
– Prioritizing high level MMFs w.r.t. project goals
– Prioritizing WCs w.r.t. MMFs
– Prioritizing test cases w.r.t. WCs and so on
32
Points To Note
• TOPSIS is ONE way of practicing VBRP
• You could even perform COTS tradeoff analyses
using it. (It’s a decision problem!)
• Use the VBRP technique that is best suited to the
situation – each technique has its pros and cons.
Choose wisely.
• Some prioritization techniques do not lend
themselves to a typical spreadsheet like analysis
• The output of some techniques could be
bucketed (categorized into the MoSCoW buckets)
or ordinal (explicitly rank ordered)
33
Conclusion
• Tools and techniques for prioritization are only
one side of the coin…
• …negotiations and discussions are the other.
The latter must be held for the former to be of
any value. Using the tool will NOT guarantee
VBRP
• There will be a Homework on VBRP posted
tonight/tomorrow, due next week. Watch the
class website.
34