A presentation highlighting how stage 3 of HBT helps to reduce defect escape and thereby reduce maintenance cost.

1. REDUCING DEFECT ESCAPE AND
THERE BY MAINTENANCE COST
M C Nagaraj
Director – Customer Excellence
in.linkedin.com/in/mcnagaraj

2. Hypothesis Based Testing (HBT)
A goal focused methodology to validation
Six-stage evaluation model (S1-S6)
S6 S1
Assess & Understand The central theme of HBT is
ANALYZE EXPECTATIONS “hypothesize potential defects that
can cause loss of expectations
and
S5 Tooling HBT
Understand
S2 prove that they will not exist”
SUPPORT CONTEXT
Devise Formulate The focus is on the goal and
PROOF HYPOTHESIS
how we shall achieve it
rather than the various activities
S3 S3
“goal-centric vs. activity-based”
Copyright STAG Software Private Limited, 2009 2

3. HBT and STEM
“outcome”
‘deliver clean software
S6 S1 GOAL quickly & cost-effectively’
Assess & Understand
ANALYZE EXPECTATIONS
D8 D1
Tooling D7 D2
S5
SUPPORT
STEM Understand
S2 “methodology”
D6 D3 CONTEXT
HBT a system of ways of doing
D5 D4
‘goal centered scientific
approach to validation’
Devise Formulate
PROOF HYPOTHESIS
S3 S3 “method”
STEM
a particular way of doing something
‘defect detection technology
from STAG’
Copyright STAG Software Private Limited, 2009 3

4. HBT – six stage personal test methodology
• Key focus in each stage
• Empowered by scientific approach using eight
disciplines (D1 to D8) of STEM
• 32 core concepts address factors like effectiveness,
consistency, scalability, efficiency, visibility and
agility of test methodology
• The outcome of each stage are well defined
Copyright 2011. STAG Software Pvt Ltd. All rights reserved. 4

5. HBT Stage 3 (Formulate Hypothesis)
Key focus: Cleanliness criteria, multiple view points,
STEM discipline D2 (Defect Hypothesis)
Problems addressed:
• Defects are escaping to production and resulted in
customer dissatisfaction
• Spending high maintenance cost than planned
• Unable to understand customer expectation upfront
• How can we prove that we have sufficient test cases
for product under test?
Copyright 2011. STAG Software Pvt Ltd. All rights reserved. 5

6. Summary
Using D2 (Defect Hypothesis) we were able to address
problems stated in previous slide
• This has well defined 4 steps
• Key deliverables: Potential defect catalog, Fault
traceability matrix
• STEM core concepts: EFF model, Defect centric
principle, Negative thinking, Orthogonality principle
This personal discipline instills a defect-centric
thinking by hypothesizing potential defects and
thereby be intensely goal focused
Copyright 2011. STAG Software Pvt Ltd. All rights reserved. 6

7. Thank You
nagaraj@stagsoftware.com
@mcnagaraj
Copyright STAG Software Pvt. Ltd., 2011