Decidi for traders & quants
Find what kills the trade before the market finds it.
Have the thesis, the risk and the data examined by independent models — so the position you take is one whose failure mode you already understand.
- Build the disconfirming case: the strongest argument the trade is wrong, argued by someone short it.
- Pressure-test the strategy for overfitting, regime change and the backtest that won’t survive live markets.
- Surface the tail risk and the liquidity trap that the Sharpe ratio quietly ignores.
- Stress-test the data and the assumptions so a confident model can’t bless a flawed signal.
- Run the position-sizing and the drawdown scenario before, not after, the bad week.
- Get a skeptic to challenge the edge — is it real, or is it crowded and already gone?
- The thesis — the strongest case it’s wrong
- Overfitting, regime change and backtest fragility
- Tail risk, drawdown and liquidity
- Data quality and the assumptions in the signal
- Position sizing and the bad-week scenario
- The edge — real, or crowded and gone?
Say a position has doubled and your thesis says hold, but the thesis was written eight months ago, the sector narrative has shifted, and every piece of news you read somehow confirms what you already own. That last part is the warning sign.
The Data Skeptic separates what has actually changed in the fundamentals from what has changed in the price — the two drift apart quietly, and confirmation bias reads both as bullish. The Quant Critic asks what the current price already assumes, because a doubled position needs the market to be more wrong now, not merely as wrong as before. The Skeptical Investor argues the exit case and the Devil’s Advocate argues the add-more case, both at full strength, so the debate is between real positions rather than a hold-by-default. The Risk Officer reframes the only question that compounds: position size relative to the portfolio now, versus when conviction was earned at half the price. The verdict names the falsifier — the specific signal that says the thesis is done.
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