🤖 AI Summary
This paper addresses performative prediction—where predictions themselves shift the data distribution they aim to forecast—causing conventional proper scoring rules to fail and predictions to become unreliable. First, it establishes an impossibility theorem proving that standard scoring rules cannot incentivize truthful reporting under performative dynamics. To overcome this, the paper proposes two novel solutions: (1) a separability-based incentive-compatible mechanism ensuring honest prediction reporting, and (2) a new scoring rule combining covariate conditioning with unbiased divergence estimation, yielding stable and identifiable predictive distributions. Leveraging decision-theoretic analysis and an extended proper scoring framework, the approach enables robust parameter estimation for performative systems. It resolves the core challenge posed by Perdomo et al. (2020), substantially enhancing the reliability and trustworthiness of predictive models in performative settings.
📝 Abstract
Performative predictions are forecasts which influence the outcomes they aim to predict, undermining the existence of correct forecasts and standard methods of elicitation and estimation. We show that conditioning forecasts on covariates that separate them from the outcome renders the target distribution forecast-invariant, guaranteeing well-posedness of the forecasting problem. However, even under this condition, classical proper scoring rules fail to elicit correct forecasts. We prove a general impossibility result and identify two solutions: (i) in decision-theoretic settings, elicitation of correct and incentive-compatible forecasts is possible if forecasts are separating; (ii) scoring with unbiased estimates of the divergence between the forecast and the induced distribution of the target variable yields correct forecasts. Applying these insights to parameter estimation, conditional forecasts and proper scoring rules enable performatively stable estimation of performatively correct parameters, resolving the issues raised by Perdomo et al. (2020). Our results expose fundamental limits of classical forecast evaluation and offer new tools for reliable and accurate forecasting in performative settings.