# On-call engineers receive twenty quality pages a week Canonical URL: Domain: Pipeline Design ยท Difficulty: medium ## Problem On-call engineers receive twenty quality pages a week. Three of them are real. The remaining seventeen train the engineer to acknowledge alerts without reading them, and the next real page lands in the same channel as a false one and is missed. The fix is not removing checks; it is tuning thresholds against historical data so a useful threshold fires somewhere between two and ten times in a 90-day window. Tune the threshold by adding a threshold-tuning transform whose name states the historical window it backtests, the target firing rate (e.g., 2-10 fires per 90 days), and a known-anomaly annotation list so previously-investigated incidents do not retrigger. ## Related - [All practice problems](https://datadriven.io/problems) - [Mock interview mode](https://datadriven.io/interview/on-call-engineers-receive-twenty-quality-pages-a-week-three-eed88602) - [System Design Interview Questions](https://datadriven.io/data-engineering-system-design) - [Data Engineering Interview Prep Guide](https://datadriven.io/data-engineer-interview-prep) - [Daily Challenge](https://datadriven.io/daily) --- Source: DataDriven (https://datadriven.io). 100% free data engineering interview prep. Live code execution against Postgres 16, Python 3.11, and Spark sandboxes. No paywall, no premium tier, no signup gate.