Flags a campaign whose click-through rate drops sharply below its own recent norm - a classic early sign of ad fatigue, a landing-page problem, new competition, or a tracking-template fault. It only counts days with real traffic, and it weighs the drop statistically, so a quiet day with a couple of clicks won't trigger a false alarm.
Defaults & settings
Z-score threshold (σ) - how many standard deviations below the baseline counts as a collapse. Default 2; higher = stricter/quieter. Adjustable 1-5.
Baseline days - how many trailing complete days to compare against. Default 13, adjustable 3-28.
Minimum impressions - ignore days under this figure to avoid noise on tiny volume. Default 100, adjustable 10-10,000.
Checks daily; 24-hour cooldown.
Example. A campaign's CTR has averaged 6.1% with modest daily wobble. Today it prints 2.8% on 900 impressions - more than 2σ below its own norm - and it's flagged on your dashboard, with the account's other campaigns unaffected.
Good to know. Because the comparison is per-campaign against its own baseline, a naturally low-CTR display-style campaign never gets judged by a high-CTR brand campaign's standard.