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 individual calibration


Distribution-Free Model-Agnostic Regression Calibration via Nonparametric Methods

Neural Information Processing Systems

In this paper, we consider the uncertainty quantification problem for regression models. Specifically, we consider an individual calibration objective for characterizing the quantiles of the prediction model. While such an objective is well-motivated from downstream tasks such as newsvendor cost, the existing methods have been largely heuristic and lack of statistical guarantee in terms of individual calibration. We show via simple examples that the existing methods focusing on population-level calibration guarantees such as average calibration or sharpness can lead to harmful and unexpected results. We propose simple nonparametric calibration methods that are agnostic of the underlying prediction model and enjoy both computational efficiency and statistical consistency.




Distribution-Free Model-Agnostic Regression Calibration via Nonparametric Methods

Neural Information Processing Systems

In this paper, we consider the uncertainty quantification problem for regression models. Specifically, we consider an individual calibration objective for characterizing the quantiles of the prediction model. While such an objective is well-motivated from downstream tasks such as newsvendor cost, the existing methods have been largely heuristic and lack of statistical guarantee in terms of individual calibration. We show via simple examples that the existing methods focusing on population-level calibration guarantees such as average calibration or sharpness can lead to harmful and unexpected results. We propose simple nonparametric calibration methods that are agnostic of the underlying prediction model and enjoy both computational efficiency and statistical consistency.


Distribution-Free Model-Agnostic Regression Calibration via Nonparametric Methods

arXiv.org Machine Learning

In this paper, we consider the uncertainty quantification problem for regression models. Specifically, we consider an individual calibration objective for characterizing the quantiles of the prediction model. While such an objective is well-motivated from downstream tasks such as newsvendor cost, the existing methods have been largely heuristic and lack of statistical guarantee in terms of individual calibration. We show via simple examples that the existing methods focusing on population-level calibration guarantees such as average calibration or sharpness can lead to harmful and unexpected results. We propose simple nonparametric calibration methods that are agnostic of the underlying prediction model and enjoy both computational efficiency and statistical consistency. Our approach enables a better understanding of the possibility of individual calibration, and we establish matching upper and lower bounds for the calibration error of our proposed methods. Technically, our analysis combines the nonparametric analysis with a covering number argument for parametric analysis, which advances the existing theoretical analyses in the literature of nonparametric density estimation and quantile bandit problems. Importantly, the nonparametric perspective sheds new theoretical insights into regression calibration in terms of the curse of dimensionality and reconciles the existing results on the impossibility of individual calibration. To our knowledge, we make the first effort to reach both individual calibration and finite-sample guarantee with minimal assumptions in terms of conformal prediction. Numerical experiments show the advantage of such a simple approach under various metrics, and also under covariates shift. We hope our work provides a simple benchmark and a starting point of theoretical ground for future research on regression calibration.


Beyond Pinball Loss: Quantile Methods for Calibrated Uncertainty Quantification

arXiv.org Machine Learning

Among the many ways of quantifying uncertainty in a regression setting, specifying the full quantile function is attractive, as quantiles are amenable to interpretation and evaluation. A model that predicts the true conditional quantiles for each input, at all quantile levels, presents a correct and efficient representation of the underlying uncertainty. To achieve this, many current quantile-based methods focus on optimizing the so-called pinball loss. However, this loss restricts the scope of applicable regression models, limits the ability to target many desirable properties (e.g. calibration, sharpness, centered intervals), and may produce poor conditional quantiles. In this work, we develop new quantile methods that address these shortcomings. In particular, we propose methods that can apply to any class of regression model, allow for selecting a Pareto-optimal trade-off between calibration and sharpness, optimize for calibration of centered intervals, and produce more accurate conditional quantiles. We provide a thorough experimental evaluation of our methods, which includes a high dimensional uncertainty quantification task in nuclear fusion.


Right Decisions from Wrong Predictions: A Mechanism Design Alternative to Individual Calibration

arXiv.org Machine Learning

Decision makers often need to rely on imperfect Given these limitations, we study alternative mechanisms probabilistic forecasts. While average to convey confidence about individual predictions performance metrics are typically available, to decision-makers. it is difficult to assess the quality of individual forecasts and the corresponding utilities. To We consider settings where a single forecaster provides convey confidence about individual predictions predictions to many decision makers, each facing a potentially to decision-makers, we propose a compensation different decision making problem. For example, mechanism ensuring that the forecasted a personalized medicine service could predict utility matches the actually accrued whether a product is effective for thousands of individual utility. While a naive scheme to compensate patients [19, 20, 2]. If the prediction is accurate decision-makers for prediction errors can be for 70% of patients, it could be accurate for Alice exploited and might not be sustainable in the but not Bob, or vice-versa. Therefore, Alice might be long run, we propose a mechanism based on hesitant to make decisions based on the 70% average fair bets and online learning that provably accuracy. In this setting, we propose an insurance-like cannot be exploited. We demonstrate an application mechanism that 1) enables each decision maker to confidently showing how passengers could confidently make decisions as if the advertised probabilities optimize individual travel plans based were individually correct, and 2) is implementable on flight delay probabilities estimated by an by the forecaster with provably vanishing costs in the airline.


Individual Calibration with Randomized Forecasting

arXiv.org Machine Learning

Machine learning applications often require calibrated predictions, e.g. a 90\% credible interval should contain the true outcome 90\% of the times. However, typical definitions of calibration only require this to hold on average, and offer no guarantees on predictions made on individual samples. Thus, predictions can be systematically over or under confident on certain subgroups, leading to issues of fairness and potential vulnerabilities. We show that calibration for individual samples is possible in the regression setup if the predictions are randomized, i.e. outputting randomized credible intervals. Randomization removes systematic bias by trading off bias with variance. We design a training objective to enforce individual calibration and use it to train randomized regression functions. The resulting models are more calibrated for arbitrarily chosen subgroups of the data, and can achieve higher utility in decision making against adversaries that exploit miscalibrated predictions.