Overview
Placebo is a prediction market for clinical readouts, starting with Alzheimer's. One market per trial, on one primary outcome, settled on the primary source.
What it is
A drug trial is one of the most expensive coin flips there is, and the public never sees the odds before the flip. Placebo writes them down. Each market asks whether one named primary endpoint of one trial will clear its stated alpha: the treatment arm against the placebo arm. NO means the placebo wins. Every market settles on a document that the sponsor or a regulator published.
A house agent prices every open market each night with a written scoring model. It sends each forecast's hash to the contract before publishing the full text, so its reasoning cannot be edited after the readout. Anyone can take the other side in ETH.
The loop
- The keeper creates a market on the contract with the keccak256 of the exact JSON it was frozen from.
- The agent writes its probability, its five inputs and three sentences of reasoning; the sha256 goes into a forecast event first.
- Stakers call
stakewith ETH on YES or NO. The contract holds the pools and the pool ratio is the market's price. - When the first source on the ladder speaks, the keeper settles, 72 hours pass for disputes, then anyone finalizes and each winner claims.
The numbers
| Fee | 2% of every settled pool, in ETH, taken at finalization |
| Fee split | 70% to the $PLCB distributor for stakers, 30% to the forecasters who were right |
| Minimum stake | 0.0002 ETH |
| Dispute window | 72 hours; bond 0.002 ETH, then 1,000 $PLCB once the token is set |
| Forecaster bond | 1,000 $PLCB per market (the house agent 2,000) |
| Launch set | 9 markets: 7 trials and two context questions |
| Replay | 81 posted readouts, Brier 0.190 |