Balancing New Features And Bug Fixes Using Scrum Practices

Prioritizing the Product Backlog

One of the key responsibilities of the Product Owner in Scrum is to prioritize the Product Backlog to maximize business value delivered by the development team. This involves carefully ranking new features and bugs based on their expected impact, cost to implement, time sensitivity and risk. Grouping related product backlog items together also allows more efficient planning.

When adding new user stories to the backlog, the Product Owner should consider factors like:

Business benefit – How much potential revenue or cost savings?
Time to market – Is there a window of opportunity?
Customer requests – What do users ask for the most?
Marketing priorities – What aligns with our messaging?

For bug reports, critical considerations include:

Severity – Does it cause data loss or block key functions?
Reproducibility – How often does the error actually occur?
Scope – How many users are impacted?
Effort level – How difficult is the fix likely to be?

Ranking factors for new features and bugs can be weighted by the Product Owner to reflect the organization’s priorities. Over time, patterns may emerge – for example, certain kinds of security and data integrity fixes may consistently rank at the top of each Product Backlog refinement. Understanding these patterns helps the team know where to focus when planning upcoming sprints.

Grouping Related Items

In addition to ranking priorities, it is also useful to group related items together in the Product Backlog. For instance:

Features that will share backend infrastructure
Bugs stemming from the same root cause
Enhancements to the same user workflow
Items dependent on completion of certain service integrations

Identifying relationships between backlog items allows more logical scheduling. If multiple stories touch the same parts of the system, doing them together minimizes duplication of analysis and rework. Understanding dependencies also improves accuracy when estimating level of effort.

Estimating Effort

During Product Backlog refinement, the Scrum team also estimates effort for each item in story points or ideal hours. Accurately gauging level of effort is challenging but critical for planning what work can be successfully completed within a series of Sprints.

Factors Impacting Effort Estimates

When estimating effort for backlog items, considerations include:

Scope uncertainty – New features may have unclear requirements, while the root cause and fix approach for bugs can be hard to anticipate.
Code quality – Sectioning poor quality code takes more effort.
Technical debt – Shortcuts like skipped tests accumulate and incur interest when being addressed.
Testing needs – Effort grows with requirements for cross-browser, device, localization and accessibility testing.

Due to these factors, effort estimates have inherent uncertainty. Teams account for this by tracking actuals against estimates and adjusting size approximations over time. Learning to estimate well is key to predictable Sprint planning.

Estimation Methods

Some common estimation techniques include:

Comparative sizing – How much effort compared to a past item of known effort?
Decomposition – Break down into tasks and estimate each task.
Affinity grouping – Categorize by effort level then compare items in each grouping.
Poker planning – Each team member proposes an estimate then values are discussed to reach consensus.

Estimation accuracy improves with experience working through items sprint-over-sprint. Over time, values become more dialed in and prediction confidence increases.

Planning the Sprint

During the Sprint Planning meeting, the Scrum team selects items from the prioritized Product Backlog to work on in the upcoming Sprint. This involves determining development team capacity, then choosing stories and bugs that can be reasonably completed given constraints.

Determining Team Capacity

As a first Sprint Planning input, the expected velocity for the team is set:

For new teams: Capacity typically set optimistically until velocity stabilizes
For mature teams: Use historical average velocity across recent sprints

Velocity (story points per sprint) accounts for both development and non-development efforts like meetings and documentation. Planning deliverables to stay within velocity prevents overburdening the team.

Selecting Product Backlog Items

Once team capacity is clear, Sprint Planning focuses on choosing what backlog items to tackle in upcoming iteration. This generally follows structure:

Walk priority list from top down selecting stories until reaching velocity limit
Consider branching off main sequence to bundle related items noted during backlog refinement
Identify bugs causing biggest user pain as mandatory fixes for inclusion

By mixing focused feature development with targeted fixes, this approach enables incrementally growing product value and stability sprint-to-sprint.

Tracking Progress

During each Sprint, the team monitors progress on delivering planned work items. This helps identify blocking issues early while there is still time to adapt plans. Typical indicators for tracking include burndown rate and velocity.

Monitoring Burndown

Burndown charts show work remaining across sprints. The x-axis represents time while the y-axis captures effort from sprint backlog items:

Ideal burndown slope trends smoothly towards zero
Faster burndown means work completed ahead of schedule
Slower burndown suggests challenges hitting target

Reviewing burndown patterns helps the Scrum Master diagnose pace issues then coach adjustments if needed.

Updating Estimates

If the initial size estimates for user stories or bugs seem off once team begins work, those backlog items can be re-estimated:

Splitting a story may decrease total points if discovered to be more complex than anticipated
Similarly, bugs found trickier to fix may need effort level increased
Conversely, overestimated items can have points reduced

Updating estimates prevents distortion of the velocity calculation used to forecast future sprint capacity.

Communicating Blocking Issues

If obstacles hinder team members from making expected progress on sprint goals, those issues should be raised transparently so the Scrum Master can help resolve:

Technical challenges – stuck on compatibility bug, slow build speeds, etc
External dependencies – waiting on customer feedback, delayed procurement, legal signoff outstanding, etc

Removing impediments accelerates delivery pacing to re-align with burndown target.

Adapting the Plan

A key Scrum emphasis is on inspecting and adapting to discover better ways of meeting goals. If tracking metrics or stakeholder needs suggest changes, the Product Owner can shift direction:

Revisiting Priorities

Development realities or business landscape shifts may require reassessing Product Backlog priorities:

High-value user stories slipping due to unexpected complexity may warrant elevation in the backlog ranks
New security issues or compliance rules could make certain fixes mandatory
Customer feedback on early UI mockups could indicate one requested theme change necessitates postponing another

By keeping priorities tied to latest insights, product relevance and stakeholder satisfaction improve.

Negotiating Scope Changes

If changes seem justified based on burndown lag, velocity trends signaling overload, or stakeholder pressing for punctuation shifts, the Product Owner can help by:

Working with stakeholders to explain current trajectory and negotiate priorities
Clarifying minimum viable feature sets
Identifying what can be pushed to subsequent sprints without downstream impacts

This protects the team from disruptive churn while satisfying stakeholders via transparency.

Maintaining Quality and Cadence

When adapting plan details, broader Scrum goals around quality and reliability should stay constant:

Technical debt and regression risks grow if quality shortcuts are taken to increase delivery velocity short-term
Stretching testing efforts to reclaim scope could enable release of defects that anger customers

By keeping sight of the big picture purpose while applying contained changes, overall development process integrity persists.

Example Code Snippets

Below are some sample snippets to illustrate key Scrum artifacts related to backlog management and sprint planning activities.

Backlog Showing Features and Bugs

This product backlog extract shows user stories and bugs mixed together in priority order with effort estimates. Related items are tagged for easier grouping when planning sprints focused on certain functionality areas.

Sprint Planning Chart

This sprint planning grid captures team capacity setting and backlog item selection based on points estimates and risk assessments. The grey indicator flags rushed items that may require de-scoping if not tracking to finish as expected.

Sprint Burndown Chart

The sprint burndown chart shows the difference between day-by-day remaining effort vs the ideal trendline had all items completed at a constant pace. Scope changes and blocking issues are annotated on relevant dates.

Velocity Chart

This historical velocity chart illustrates the variability and estimate accuracy improvement that can occur across sprints as team experience with backlog items grows.

Key Takeaways

Some core themes around effectively balancing new feature development with bug fixing when using Scrum practices include:

Proactively prioritizing the Product Backlog according to business value, customer needs and risk considerations guides what gets focus across sprints
Grouping related items during backlog refinement enables more efficient sprint planning
Regularly revisiting and revising backlog item estimates improves accuracy over time
Monitoring team velocity and sprint burndown provides visibility for when mid-course adaptions may be prudent
Openness to changing sprint commitments based on new insights is key to maximizing ROI as realities shift

By leveraging Continuous Inspection, Adaptation and Transparency principles, Scrum teams can achieve an optimal balance between building new capabilities and addressing quality defects over multiple development cycles.