A daypart bid multiplier rebuilt from log data lifted conversions 18%

A daypart bid multiplier rebuilt from log data lifted conversions 18%

A performance buyer used flat bids around the clock. Log-level analysis showed clearing prices and conversion rates moved on opposite schedules.

1. They bucketed every auction by hour and computed two curves: median clearing price and post-click conversion rate.
— Conversion rate peaked 22:00 to 01:00; clearing prices peaked 18:00 to 21:00 (prime-time competition).
2. The two peaks were offset by several hours, so flat bidding overpaid during expensive low-converting hours and underbid during cheap high-converting ones.
3. They built hourly bid multipliers: -20% in the 18:00 to 21:00 window, +25% in 22:00 to 01:00.

Evidence: at flat total spend, conversions rose 18% and cost per acquisition fell 15%, because budget moved into hours where the impression was both cheaper to win and more likely to convert.

Why it matters: clearing price and conversion value rarely peak at the same hour. A single flat bid averages over that mismatch. Daypart multipliers, built from your own log-level curves, buy the hours where the two align in your favor.