2. Background
Introduction
Well defined test performance indicators support decision making by management and also provide a methodi-
cal approach to assess the efficiency and effectiveness of current test processes. Assessment of software quality
and process efficiency gets skewed, resulting in wrong decisions, when proper test performance indicators and
measurements are not defined and agreed.
Although there are several software test performance indicators defined by practitioners, researchers and
professionals, they may be either used in isolation or worse, wrong indicators may be used. This white paper
describes the metrics used by Idexcel, and how they help our clients.
Test Performance Indicators (TPIs) are high level metrics of effectiveness or efficiencies used to guide and
control progressive test development, test process and product quality. Idexcel has adopted the Test Maturity
Model (TMMi) process model for all its testing projects, and TPI’s are defined in line with the best practices
recommended by TMMi. While developing these TPI’s, Idexcel has established procedures for data collection,
owners, storage, analysis and reporting of TPI’s. The key project stakeholders periodically analyze the reported
data and take necessary action.
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Test Performance Indicators
3. Test Performance Indicators
Used by Idexcel
In line with industry practices, Idexcel has broadly classi-
fied TPI’s into two broad categories: “Test Process
Indicators”, and “Product Quality Indicators”.
Test Process Indicators (TPIs)
One of the objectives of Idexcel’s Test Policy is to
provide a cost effective and efficient software testing
process to its customers. To meet this objective, we
continuously measure the effectiveness and efficiency
of software testing. This helps in assessing the quality
and effectiveness of the process and productivity of the
personnel involved in testing activities and this in turn
helps to improve the software testing procedures,
methods, tools and tasks. Gathering these TPI’s help
Idexcel to analyze the data and learn from historical
data, resulting in improved software testing maturity.
Product Quality Indicators
The TPI’s provide insight into test state and testing
status of a software product to engineers and project
stakeholders and are generated by test execution, code
fixes and deferment. Using these metrics, we measure
the product test state and indicative the level of quality.
Based on experience gained by working with several
customers, we have redefined product quality metrics
into two parts, ‘Product Quality TPI’s and ‘Customer
Oriented Indicators’.
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We use test performance indicators for:
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Identifying testing strengths, weaknesses and areas of
improvements
Analyzing risk
Benchmarking for future process optimization
Taking product and process decisions
Analyzing the current state of organization’s testing
processes
Determining customer involvement and satisfaction
Controlling and monitoring of test process
Measuring test productivity and effectiveness.
Test Performance Indicators
The traditional approach cannot cope with the fast
pMeasuring process effectiveness is an objective, order-
ly method of quantifying, assessing, adjusting and
ultimately improving the testing process. We collect
data for each project or program and analyze them at
regular intervals to assess software quality and process
performance throughout the software test lifecycle and
create a baseline and guidance for future projects.
Collect Data and store it
in a common repository
Evolve the process based
on the analysis
Evolve the process based
on the analysis
Review the data and
ensure only quality data
is available for analysis
Analyze and prepare
reports and present them
to management
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Effort Variance
This is a process efficiency indicator which helps in
understanding any extra effort injected into a testing
project to complete the activities which were planned at
the beginning of the project. This indicator combined
with the phase wise effort indicator gives insights to
address the problematic phases that must be improved
in terms of efficiency and effectiveness. On the contrary,
if investigations reveal that the benchmarking used for
initial efforts estimation needs tweaking based on
changed circumstances, management can take the
necessary action to revise the benchmark.
Negative results are a good sign for management, as
they can use these negative results to revise the organi-
zation wide bench mark for effort estimation of similar
projects.
Defects Slippage
This is one of the most important ‘Process Effectiveness’
indicators that helps in identifying the effectiveness of
the testing process adopted by an organization. Defects
Slippage is directly related to the company’s reputation,
warranty costs, future business, contract requirement
and customer satisfaction. Idexcel regularly monitors
this indicator by project and analyzes the data to identi-
fy and plug gaps in the existing testing process.
Defect Removal Efficiency
This is a ‘Process Efficiency’ indicator that indicates the
defects removed per time unit (hours/-
day/weeks/phase)
Idexcel has derived this indicator directly from the orga-
nization’s debug policy, and this indicator denotes the
efficiency of defect removal methods and is also an
Test Performance Indicators
KeyTest Performance Indicators
Used by Idexcel
Phase-Wise Testing Effort
This Process efficiency indicator helps in identifying the
intensive effort areas during prevention, verification
and validation attributes in the project. Prevention
activities include planning, training and validation &
verification activities and include time spent on tasks
such as test case walkthroughs, reviews, environment
set up, testing, test requirement, re-test etc. Examples
of phase-wise effort in testing is shown in the chart
below.
Cost Variance
This is a process efficiency indicator which helps in
understanding actual cost versus planned and budgeted
expenditure. Whenever testing cost overshoots the
budgeted cost, management can analyze and gain
in-depth understanding of the lessons learned during
the given project, and this understanding can be used to
l the testing costs of future projects. However, due to
changes in some internal or external factors, the bench-
mark used for creating budgets may become outdated,
and hence overshoot.
Review
Rework
Test Execution
Environment set up
Test Reporting
Documentation
Planning
Training
50%
7%
13%
8%
9%
5% 4% 4%
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indirect measurement of the quality of a product. We
calculate these indicators at every stage of the software
development lifecycle and maintain the DRE for differ-
ent stages such as unit, integration, System, UAT, opera-
tional readiness, documentation.
Defect Rejection Ratio
Some of the assumptions made during the process
controlled software development for testing activities
are:
1. Testers understand the application and minor details
of the requirements
2. All decisions related to requirements are well com-
municated to the testers, and revised documents are
shared with them
3. Testing happens in a controlled test environment
4. Configuration management is in place and testers are
getting the intended build for testing
5. Testers are well trained in application process and
business logic.
A defect initially raised by a tester could be later reject-
ed if any one of the above assumption goes wrong. The
main objective of this ‘Process Effectiveness’ indicator is
to ensure that testers correctly understand the require-
ments and get involved in all the phases of the software
development lifecycle. Too many rejected defects result
in inefficiency, and indicate the lapse in process effec-
tiveness.
Test Execution Productivity Trend
This Process efficiency indicator helps find the produc-
Test Performance Indicators
tivity of the test team. Productivity may be defined as
test cases executed by a team per unit time (hours/-
days/weeks/phase/release). This indicator helps in
identifying the problematic areas impacting a team’s
productivity and helps take remedial action.
Test Coverage
The purpose of the Test Coverage indicator is to assess
whether sufficient testing has been performed, and
identify areas that may require additional testing. This
metric measures the number of test cases tested
successfully against total number of test cases planned
for each product component at major milestones of the
software development life cycle. This indicator tells us,
what is missing much better than what is done well.
Scope Volatility
After the requirements and deliverables are signed off,
requirement volatility becomes a major factor, especial-
ly on testing tasks in a program/project. Requirement
volatility can be categorized into the following types:
addition to existing requirements, deletion from existing
requirements, change in scope to an existing require-
ment and shift in design. Under the definition of scope
Test coverage Metric Example
0% 20% 40% 60% 80% 100% 120%
Admin UI
Website UI
3rd Party Integration
Stored Procedure
Billing
Data Migration
Settlement
Configuration
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volatility, we can also include specific issues related to
testing such as re-opening fixed defects, multiple builds
handed over to a testing team and change in configura-
tions.
These indicators not only measure the test team’s
efficiency against changes in project dynamics, but also
demonstrate process stability and improvements
required in the existing process. The following diagram
shows the scope volatility caused by different reasons.
Origin of Defects
This is a ‘Test Effectiveness’ indicator showing the
software development phase or activity in which the
defect occurred. This indicator helps in analyzing:
1. Major problem areas in project/program or company-
wide projects/programs,
2. Patterns in defects
3. Scope to build a baseline that characterize errors,
faults or failures
Test Performance Indicators
4. Pattern associated with defects that will support
prediction
The classification of software development phases
contributing to defects is showing in the example below.
Requirement
Specification
Design
Code
Environment
Others
51%
7% 13%
14%
10%
5%
0%
20%
40%
60%
80%
100%
120%
Requirement
Change
Design Multiple builds for
same version
Configuration
changes
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Defect Priority
This indicator provides insight into the quality of the prod-
uct under test. High priority defects indicate a low product
quality. This information helps project stake holders to
make release decisions based on the number of defects
and their priority levels. Defect priorities may be classified
as “Critical”, “Major”, “Minor”, “Medium”, and “Low” and
must be consistently applied across different projects in an
organization.
Defect Distribution across components
This indicator gives information about the way defects are
distributed across the various components of the system.
We also assign priorities for different components or
sub-systems, helping the project stakeholders to assess
risks and address issues in components or subsystems that
are critical to the product, ahead of others.
Examples of
Product Quality Metrics
Used by Idexcel
Test Performance Indicators
Critical
Major
Minor
Medium
Low
Time to Fix Defects
This indicator gives insight into the effort required to fix
defects by priority. This is the time elapsed between
reporting a defect and closing the defect after retesting.
Idexcel represents this with two sets of charts: a bar chart
with current values with each priority and historical trend
over all priorities. This is a key indicator for maintainability
of the product and serves as an input to project mainte-
nance cost and patch schedules.
Status Indicators
These indicators give status of test execution per unit time.
These indicators give management the overall status of
test activity and product quality. This indicator includes
“number of test cases”, “Number of test cases executed”,
“Number of Test cases passed”, “and “Number of Test
cases failed”.
Defect Arrival Rate
This indicator gives a high level status of active defects for
a project along with daily defect open rates, showing the
trend in the quality of the product. Ideally, the defects
reported should show a declining trend over time especial-
ly when nearing the UAT/production release. Management
and project stakeholders can take product release
decisions based on this indicator.
Cumulative Defects by Status
This indicator helps to evaluate the number of defects by
status in a particular release. This indicator can ensure that
all the known defects have been corrected and action
plans are in place for open defects. This indicator
combined with Defect Removal Rate indicator helps in
making release decisions better.
35%
10%
15% 10%
30%
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Examples of decision criteria we set for a particular
program are:
1. Zero open critical defects
2. Less than 5% open defects with stake holders’ approval
and workaround
3. Open minor defects are less than the agreed numbers
4. Defect arrival rate shows a declining trend towards zero
over the last few measurement periods.
Metrics or performance indicators discussed so far
address the needs of testing process product quality. How-
ever, we believe that successful customer experience
management requires collection and analysis of different
types of customer related metrics. Customer related
metrics helps us to manage customer relationships and
identify improvement opportunities for improving
customer satisfaction.
Some of the customer related metrics are discussed
below.
Customer Problem Metrics
These metrics measure the problems that customers
encountered while using the product. We consider all
Test Performance Indicators
Examples of
Customer Related Indicators
Used by Idexcel
problems encountered by our customers while using the
software product, as problems with the software and not
just the valid defects. Problems that are not valid defects
could be usability problems, ambiguous documentation
etc. By carefully analyzing these metrics, we can:
• Improve the software development life cycle processes
and reduce product defects
• Reduce the non-defect-oriented problems by improving
all aspects of a products (such as usability, documenta-
tion), customer education, and support.
Financial Performance Index
These metrics will help us in achieving a lower targeted
level of budget spend on testing, and help us to turn
testing into a more efficient process.
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Conclusion
Continuous improvement is the key to success for any process. Well defined test performance indicators
provide a methodical approach to assess the efficiency and effectiveness of the current test processes and
significantly improve the testing process in terms of coverage, time and quality.
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Test Performance Indicators