Calibration of Time-Series Forecasting: Detecting and Adapting Context-Driven Distribution Shift

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Main Authors: Chen, Mouxiang, Shen, Lefei, Fu, Han, Li, Zhuo, Sun, Jianling, Liu, Chenghao
Format: Preprint
Published: 2023
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author Chen, Mouxiang
Shen, Lefei
Fu, Han
Li, Zhuo
Sun, Jianling
Liu, Chenghao
author_facet Chen, Mouxiang
Shen, Lefei
Fu, Han
Li, Zhuo
Sun, Jianling
Liu, Chenghao
contents Recent years have witnessed the success of introducing deep learning models to time series forecasting. From a data generation perspective, we illustrate that existing models are susceptible to distribution shifts driven by temporal contexts, whether observed or unobserved. Such context-driven distribution shift (CDS) introduces biases in predictions within specific contexts and poses challenges for conventional training paradigms. In this paper, we introduce a universal calibration methodology for the detection and adaptation of CDS with a trained model. To this end, we propose a novel CDS detector, termed the "residual-based CDS detector" or "Reconditionor", which quantifies the model's vulnerability to CDS by evaluating the mutual information between prediction residuals and their corresponding contexts. A high Reconditionor score indicates a severe susceptibility, thereby necessitating model adaptation. In this circumstance, we put forth a straightforward yet potent adapter framework for model calibration, termed the "sample-level contextualized adapter" or "SOLID". This framework involves the curation of a contextually similar dataset to the provided test sample and the subsequent fine-tuning of the model's prediction layer with a limited number of steps. Our theoretical analysis demonstrates that this adaptation strategy can achieve an optimal bias-variance trade-off. Notably, our proposed Reconditionor and SOLID are model-agnostic and readily adaptable to a wide range of models. Extensive experiments show that SOLID consistently enhances the performance of current forecasting models on real-world datasets, especially on cases with substantial CDS detected by the proposed Reconditionor, thus validating the effectiveness of the calibration approach.
format Preprint
id arxiv_https___arxiv_org_abs_2310_14838
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Calibration of Time-Series Forecasting: Detecting and Adapting Context-Driven Distribution Shift
Chen, Mouxiang
Shen, Lefei
Fu, Han
Li, Zhuo
Sun, Jianling
Liu, Chenghao
Machine Learning
Artificial Intelligence
Recent years have witnessed the success of introducing deep learning models to time series forecasting. From a data generation perspective, we illustrate that existing models are susceptible to distribution shifts driven by temporal contexts, whether observed or unobserved. Such context-driven distribution shift (CDS) introduces biases in predictions within specific contexts and poses challenges for conventional training paradigms. In this paper, we introduce a universal calibration methodology for the detection and adaptation of CDS with a trained model. To this end, we propose a novel CDS detector, termed the "residual-based CDS detector" or "Reconditionor", which quantifies the model's vulnerability to CDS by evaluating the mutual information between prediction residuals and their corresponding contexts. A high Reconditionor score indicates a severe susceptibility, thereby necessitating model adaptation. In this circumstance, we put forth a straightforward yet potent adapter framework for model calibration, termed the "sample-level contextualized adapter" or "SOLID". This framework involves the curation of a contextually similar dataset to the provided test sample and the subsequent fine-tuning of the model's prediction layer with a limited number of steps. Our theoretical analysis demonstrates that this adaptation strategy can achieve an optimal bias-variance trade-off. Notably, our proposed Reconditionor and SOLID are model-agnostic and readily adaptable to a wide range of models. Extensive experiments show that SOLID consistently enhances the performance of current forecasting models on real-world datasets, especially on cases with substantial CDS detected by the proposed Reconditionor, thus validating the effectiveness of the calibration approach.
title Calibration of Time-Series Forecasting: Detecting and Adapting Context-Driven Distribution Shift
topic Machine Learning
Artificial Intelligence
url https://arxiv.org/abs/2310.14838