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Marc-Olivier Boldi

Publications and source records attributed to Marc-Olivier Boldi.

3 recordsLinked to original sources

SEMF: Supervised Expectation-Maximization Framework for Predicting Intervals

This work introduces the Supervised Expectation-Maximization Framework (SEMF), a versatile and model-agnostic approach for generating prediction intervals with any ML model. SEMF extends the Expectation-Maximization algorithm, traditionally used in unsupervised learning, to a supervised context, leveraging latent variable modeling for uncertainty estimation. Through extensive empirical evaluation of diverse simulated distributions and 11 real-world tabular datasets, SEMF consistently produces narrower prediction intervals while maintaining the desired coverage probability, outperforming traditional quantile regression methods. Furthermore, without using the quantile (pinball) loss, SEMF allows point predictors, including gradient-boosted trees and neural networks, to be calibrated with conformal quantile regression. The results indicate that SEMF enhances uncertainty quantification under diverse data distributions and is particularly effective for models that otherwise struggle with inherent uncertainty representation.

stat.ML↗

Intraday Retail Sales Forecast: An Efficient Algorithm for Quantile Additive Modeling

With the ever increasing prominence of data in retail operations, sales forecasting has become an essential pillar in the efficient management of inventories. When facing high demand, the use of backroom storage and intraday shelf replenishment is necessary to avoid stock-out. In that context, the mandatory input for any successful replenishment policy to be implemented is access to reliable forecasts for the sales at an intraday granularity. To that end, we use quantile regression to adapt different patterns from one product to the other, and we develop a stable and efficient quantile additive model algorithm to compute sales forecasts in an intradaily context. Our algorithm is computationally fast and is therefore suitable for use in real-time dynamic shelf replenishment. As an illustration, we examine the case of a highly frequented store, where the demand for various alimentary products is accurately estimated over the day with the help of the proposed algorithm.

stat.AP↗

Improving the local scoring algorithm using gradient sampling

We adapt the gradient sampling algorithm to the local scoring algorithm to solve complex estimation problems based on an optimization of an objective function. This overcomes non-differentiability and non-smoothness of the objective function. The new algorithm estimates the Clarke generalized subgradient used in the local scoring, thus reducing numerical instabilities. The method is applied to quantile regression and to the peaks-over-threshold method, as two examples. Real applications are provided for a retail store and temperature data analysis.

stat.ME↗