On-Call Rotation Fairness Math

Rotation should be fair. The math that proves it.

Metrics that measure fairness

Pages per engineer per quarter. The headline metric.

Weekend and off-hours pages per engineer. The pain metric. Off-hours pages weigh more than business-hours pages.

Length of pages. Some pages take 5 minutes; some take 5 hours. Per-engineer minutes-on-page over a quarter.

Acceptable variance

Within 20% across engineers in the same rotation. More than 20% means imbalance worth investigating.

Some variance is natural. Some shifts have more pages; some engineers happen to be on for active incidents.

Sustained imbalance over multiple quarters is the issue. Random variance over one quarter is noise.

Common causes of imbalance

Senior engineers carry more pages because they're trusted with the noisier services. Distribute or compensate.

Rotation gaps from vacation or leave that aren't covered properly. Backup on-call should equalise.

Geographic clustering: an engineer in a bad timezone gets more off-hours pages. Compensate or rotate timezones.

Responding to imbalance

Reshuffle the rotation. Different shift patterns; different engineer pairings.

Compensation for outliers. Time off, stipend, recognition. The work is real; the compensation should match.

Address the cause: noisy services need tuning, not just rotation tricks.

Quarterly fairness review

Per engineer in each rotation: pages, off-hours pages, page-minutes. Ranked.

Outliers explained. New engineer ramping up; service that hit a bad week; vacation coverage.

Action items. Reshuffle, compensate, fix the underlying noise. Track quarter over quarter.