QA Engineer interview question
What quality metrics do you use?
Use outcome and flow metrics such as escaped defects by impact, change failure rate, time to detect and recover, flaky-test rate, coverage of critical risks and customer failure rate; avoid raw test counts as quality.
Direct answer
What a strong answer covers
How it works
Quality metrics should describe outcomes users and the business feel, and the flow that produces them. Escaped defects weighted by severity show what testing missed; change failure rate and time to detect and recover show how safely changes reach production; customer-reported failure rate and support volume per release show the experience; flaky-test rate and suite runtime show whether the feedback loop is trusted and fast; and coverage of the identified high-risk areas shows where testing effort goes. Raw counts of tests written or bugs found say nothing about quality and invite gaming. Each metric is tracked as a trend and discussed against the changes that moved it.
Example
A team’s quarterly quality review showed escaped defects down from 14 to 6 with none above sev-2, change failure rate steady at 5 percent, time to recover down from 40 to 12 minutes after the rollback drills, flaky-test rate up to 4 percent, which triggered a cleanup, and a coverage map showing the new billing module had no exploratory sessions yet. The number of tests in the suite was not on the slide.
Common mistakes
- Reporting test counts and code coverage percentages as if they were quality.
- Measuring escaped defects without severity so a typo counts like a data loss.
- Tracking a metric nobody acts on.
A useful answer structure
Answer from your own work.
Do not memorise a script: use only examples you can explain honestly in follow-up questions.
Open the desktop workspace and rehearse a clear answer in your own words.