Skip to content
Qualflare

Test Observability

Mean time to detection (MTTD)

Also known as: MTTD, time to detect

Mean time to detection (MTTD) is the average time between a defect being introduced and a test or signal catching it — a measure of how fast your quality feedback loop is.

In a testing context, MTTD captures how long a regression survives before something turns red. Shorter is better: a bug caught on the commit that introduced it is cheap to fix; one caught a week later, after more changes pile on top, is expensive and risky.

You shorten MTTD by running the right tests sooner (shift-left), giving fast feedback in CI, and making failures legible so the cause is obvious the moment a test breaks.

  • Measures how long a defect survives before a test or signal catches it.
  • Shorter MTTD means cheaper fixes — a bug caught on its own commit costs far less.
  • Shortened by shift-left testing, fast CI feedback, and legible failures.

Frequently asked

How is MTTD related to DORA metrics?

MTTD is a quality-feedback companion to DORA’s delivery metrics. Faster detection shortens lead time for changes and lowers change failure rate, because regressions are caught before they accumulate. DORA frames the keys of delivery performance; MTTD measures how quickly your tests surface a problem within that loop.

Related terms

Shift-left testing Test observability Quality gate DORA metrics

Sources

See it in your own test results

Qualflare detects flaky tests, clusters failures by root cause, and scores release risk from the test results you already produce in CI. Start free.

Start free with Qualflare

← Back to the testing & observability glossary.

Last reviewed June 26, 2026