Purpose
A Blocking Defect is defined to be a high priority defect that is currently open (not closed) and has an associated
requirement. The assumption is that work on the requirement cannot proceed until the defect is resolved.
Teams monitor blocking defects in order to understand their impact on velocity.
Definition
Count: Total Number of Blocking Defects in each iteration.
Group by severity.
Analysis
A good way to monitor blocking defects is to use a trend line. Plot the number of blocking defects on the Y axis and
iterations on the X axis. Monitor blocking defects by severity to ensure high severity defects are removed
first. Create a drill down report to see blocking defects with their associated requirements.
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Expected trend - The trend line should slope downward indicating that the number of blocking
defects is decreasing.
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Upward slope - This trend indicates that work on an increasing number of requirements is being
delayed.
A high number of blocking defects in the backlog may indicate that:
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The team does not collaborate well (e.g. no collaboration between the development and testing teams). Team members
do not work to remove road blocks in order to increase team velocity.
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The project manager is not doing a good job at allocating the resources needed to remove road blocks.
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The team focuses on delivering new functionality without considering the quality of the system.
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The risk management process may not be effective. The risks associated with not resolving the road blocks are not
well understood.
The team needs to focus on addressing any uncertainty in the project that is impeding progress. They must also work to
communicate problems and dependencies. Too many blocking defects will affect the team's
velocity, impacting the project schedule and cost.
In the example below, which describes the number of defects for the Smarter-Living project in the Smarter Planet
program, blocking defects are increasing late in the lifecycle. This can have serious implications to the project in
terms of schedule, cost, and scope.
Frequency and reporting
The team reviews Blocking Defects at the end of each iteration to help identify trends.
Collection and reporting tools
Collect data for this metric in IBM® Rational® Team Concert® or IBM® Rational® Quality Manager®. IBM®
Rational® ClearQuest® and IBM® Rational® Insight® report on this metric.
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