Describe a specific moment when the error budget influenced a decision: "We had consumed 80% of our monthly error budget, so we paused feature releases and focused on stability."
Look for: understanding the SLI/SLO/SLA hierarchy, choosing meaningful SLIs (latency, availability, correctness), setting realistic SLOs based on user expectations, using error budgets to balance reliability and velocity, and what happens when the budget is exhausted. Best candidates describe a real example where error budget data changed a team decision.
Core SRE concept. Candidates who cannot explain error budgets are not practicing modern SRE. Ask: "What do you do when the error budget is exhausted but the team wants to ship?"