Software and IT are process businesses too. Work flows through queues and reviews, defects escape, systems fail, and changes go out with more or less checking. Ideas from Lean and quality engineering, such as limiting work in progress, measuring where defects are found, running blameless reviews, and building checks into the pipeline, translate well.
This hub groups the site's software and IT guides, tools, and templates with the general quality and improvement material that fits best. Start with the learning path, or jump to the tool you need.
Start with Defect Prevention Open the Flow Metrics Calculator
About This Hub
Suggested Learning Path
- Defect Prevention and Code Review — find defects earlier and measure how well you remove them
- Defect Removal Efficiency Calculator — calculate DRE and cost by stage
- Flow Metrics and WIP Limits — measure cycle time and forecast with percentiles
- Flow Metrics Calculator — see what a WIP limit would do
- Incident Management and Blameless Postmortems — learn from outages with SLOs and error budgets
- Quality Gates and Delivery Metrics — build fast feedback and track the DORA measures
- Definition of Done and Quality Gate Checklist — record gates and delivery metrics
Quality in Software and IT Guides
Defect Prevention and Code Review
Layers of prevention, effective reviews, and defect removal efficiency.
Flow Metrics and WIP Limits
Cycle time, throughput, Little's Law, and forecasting with percentiles.
Incident Management and Blameless Postmortems
Incident measures, SLOs, error budgets, and postmortems.
Quality Gates and Delivery Metrics
Automated gates, a definition of done, and the four DORA metrics.
Kanban Pull Systems
Pull signals and WIP limits.
MTBF, MTTR, and Availability
Reliability measures for systems and services.
5 Whys Root Cause Analysis
Dig past the first cause after a failure.
FMEA
Analyze how a system or change could fail.
Mistake-Proofing
Design errors out with better tooling and defaults.
8 Wastes (DOWNTIME)
The wastes behind rework, waiting, and handoffs in delivery.
PDCA Cycle
Improve in small, tested steps.
Theory of Constraints
Find the bottleneck that limits delivery.
Tools and Calculators
Defect Removal Efficiency Calculator
DRE, cost of defects, and the saving from finding escapes earlier.
Flow Metrics Calculator
Throughput, percentiles, histogram, and WIP limit effect.
Reliability and Availability Calculator
Availability, downtime, and redundancy effects.
Pareto Chart Builder
Rank defect causes and incident causes.
Risk Matrix Builder
Plot risks by likelihood and impact.
Monte Carlo Simulation Studio
Simulate delivery and schedule uncertainty.
Control Chart Selector
Choose a control chart for your metric.
Project ROI Calculator
Compare improvement options financially.
Templates
Blameless Postmortem Template
Incident summary, timeline, contributing factors, and actions.
Definition of Done and Quality Gate Checklist
Gates, release log, and DORA delivery metrics.
8D Problem Solving Report
A structured report for significant problems.
A3 Problem Solving Template
A one-page problem-solving report.
PDCA Learning Workbook
Record improvement cycles and what was learned.
Pareto Analysis Data Template
Rank causes of defects and incidents.
SPC Control Chart Data Sheet
Chart a delivery or quality metric over time.
PFMEA Template
Failure mode analysis for a process.
Software Quality and Delivery Terms You Will Meet
| Term or framework | What it means for improvement work |
|---|---|
| Defect removal efficiency (DRE) | The share of all defects found before release. |
| Shift left | Moving checks earlier in the delivery process, closer to where defects are introduced. |
| Cycle time and lead time | Time from start of work to done, and from request to delivery. |
| WIP limit | A cap on items in progress, to reduce waiting and expose bottlenecks. |
| SLI, SLO, and error budget | A service measure, its target, and the allowed unreliability (100% minus the SLO). |
| MTTD, MTTA, and MTTR | Mean time to detect, acknowledge, and restore, for incidents. |
| Blameless postmortem | A review of an incident that focuses on system and process causes, not blame. |
| DORA metrics | Deployment frequency, lead time for changes, change failure rate, and time to restore service. |
| Quality gate | An automated or manual checkpoint a change must pass to move on. |
| Definition of done | The agreed criteria for a change or release to count as finished. |
Body of Knowledge Definitions
Quality in Software and IT Hub: Frequently Asked Questions
Do Lean and quality methods apply to software?
Yes. Limiting work in progress, mapping and shortening flow, measuring defects by where they are found, root cause analysis, and small tested changes all apply to software delivery and IT operations, adapted to the fact that the work is knowledge work and often continuous.
Where should a software team start?
Measure before changing. Record where defects are found to calculate defect removal efficiency, collect cycle times to see the distribution, and review incidents in blameless postmortems with action items. Then choose one improvement, such as smaller changes or an automated gate, and track the effect.
Is this content security or engineering guidance?
No. It is educational material about quality and process-improvement methods, written from a quality and operations perspective. It does not replace your organization's policies, applicable standards, or qualified professional judgment, and changes to production systems and controls should be reviewed by qualified people.
Sources and Further Reading
- Nicole Forsgren, Jez Humble, and Gene Kim, Accelerate; DORA State of DevOps reports.
- Betsy Beyer and colleagues (eds.), Site Reliability Engineering; John Allspaw, "Blameless PostMortems and a Just Culture."
- David J. Anderson, Kanban; Mary and Tom Poppendieck, Lean Software Development.
- Capers Jones, Applied Software Measurement; Steve McConnell, Code Complete.
- ASQ Certified Software Quality Engineer Body of Knowledge.