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Privacy is moving ad decisions onto the device. The auction runs locally, next to the context it scores.
The budget still lives on a server.
So every device bids against the balance it saw at its last sync. Between syncs, campaigns spend money they no longer have.
I simulated how much that costs: 50 devices, 36 campaigns, about 300,000 auctions per run, 30 seeds per cell, budgets frozen before evaluation. Even pacing, second-score payment:
- Sync every tick: spend lands 18% over budget (32% with iPinYou-calibrated values).
- Sync every 10 ticks: 5.8 times the budget.
- Sync every 50 ticks: 17.7 times the budget (10.1 times with iPinYou-calibrated values).
Zero-lag sync stays within about 1%. The lag alone does the damage.
The incentive side runs the other way. With second-score payment and zero lag, 98% of auctions are manipulable (92% with iPinYou values). Switch the payment rule to critical-bid and that drops to 0 at every sync interval, in both setups.
Sync fixes the budget. The payment rule, not the sync interval, is what removes manipulability.
All 12 result sets are on the Hub, plus the 50,808 context labels every run samples from.
Paper: When Privacy Moves ML-Mediated Decisions On Device: Information and Incentive Misalignment in Auctions (2609.33312)
Dataset: skelfresearch/on-device-auction-audit
Code: https://github.com/sarkar-dipankar/on-device-auction-audit
If your ads stack moves on device, how often does the device learn its budget?
The budget still lives on a server.
So every device bids against the balance it saw at its last sync. Between syncs, campaigns spend money they no longer have.
I simulated how much that costs: 50 devices, 36 campaigns, about 300,000 auctions per run, 30 seeds per cell, budgets frozen before evaluation. Even pacing, second-score payment:
- Sync every tick: spend lands 18% over budget (32% with iPinYou-calibrated values).
- Sync every 10 ticks: 5.8 times the budget.
- Sync every 50 ticks: 17.7 times the budget (10.1 times with iPinYou-calibrated values).
Zero-lag sync stays within about 1%. The lag alone does the damage.
The incentive side runs the other way. With second-score payment and zero lag, 98% of auctions are manipulable (92% with iPinYou values). Switch the payment rule to critical-bid and that drops to 0 at every sync interval, in both setups.
Sync fixes the budget. The payment rule, not the sync interval, is what removes manipulability.
All 12 result sets are on the Hub, plus the 50,808 context labels every run samples from.
Paper: When Privacy Moves ML-Mediated Decisions On Device: Information and Incentive Misalignment in Auctions (2609.33312)
Dataset: skelfresearch/on-device-auction-audit
Code: https://github.com/sarkar-dipankar/on-device-auction-audit
If your ads stack moves on device, how often does the device learn its budget?
