Known unknowns are things a team knows it doesn't know: factors it's aware of but can't yet quantify or understand. They sit alongside known knowns, unknown knowns and unknown unknowns in a simple matrix of knowledge.
Why it matters: Naming known unknowns makes the gaps in a team's knowledge visible, so they can be investigated rather than ignored. Testing often turns known unknowns into understood risks.
In practice: Testers list open questions and assumptions, then use experiments, data and conversations to answer them. Things can also move the other way: testing may reveal that something thought to be known was really a known unknown.
Examples:
- Knowing a third-party service has rate limits but not yet knowing what they are.
- Listing open questions about performance before a release so they can be investigated.
Common pitfalls:
- Treating known unknowns as low priority because they're hard to estimate.
- Forgetting to revisit them, so they quietly become assumptions.
What are the four types of known and unknown? Known knowns (understood risks), known unknowns (gaps we're aware of), unknown knowns (implicit knowledge nobody has written down) and unknown unknowns (things nobody has considered).
