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Tweedie's Formula and Score-Driven Updating

Peter Reinhard Hansen, Chen Tong

arXiv 15 May 2026 · Econometrics

arXiv:2605.15902 · PDF · DOI · OpenAlex · Extracted main text

Abstract

Score-driven models update time-varying parameters using conditional likelihood scores. This paper develops a Bayesian interpretation of such updates through Tweedie's formula, which connects posterior mean corrections with marginal scores. In Gaussian signal extraction, this gives an exact posterior-correction identity. For natural exponential families, related identities characterize posterior means in natural- and expectation-parameter spaces. Building on these identities, we show that conjugate Bayesian filtering in expectation space coincides exactly with an inverse-Fisher-scaled conditional score update under local precision discounting. For general conditional densities, the exact Bayesian correction involves a generally unavailable predictive-marginal score. A local Gaussian approximation shows that the conditional likelihood score provides the leading approximation to this posterior correction; under local precision discounting, the predictive covariance becomes proportional to inverse Fisher information, yielding the familiar inverse-Fisher-scaled score recursion. The results clarify when score-driven updates are exact Bayesian filters and when they should instead be viewed as tractable local approximations.

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28
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Most heavily cited references

The works this paper leans on most, across its whole bibliography — not restricted to papers in our corpus. Ranked by composite intensity, which combines how often a work is mentioned, how many sections mention it, and how much of that falls in the main text rather than the appendix.

ReferenceIntensityMentionsSectionsMain text
1de Punder, R., Dimitriadis, T., and Lange, R.-J (2026) Expected Kullback-Leibler-based characterizations of score-driven updates0.92843100%
2Blasques, F., Koopman, S. J., and Lucas, A (2015) Information-theoretic optimality of observation-driven time series models for continuous responses0.73732100%
3Efron, B (2011) Tweedie's formula and selection bias0.73732100%
4Gorgi, P., Lauria, C. S. A., and Luati, A (2024) On the optimality of score-driven models0.73732100%
5Robbins, H (1956) An empirical Bayes approach to statistics0.64422100%
6Tweedie, M. C. K (1984) An index which distinguishes between some important exponential families0.64422100%
7Creal, D., Koopman, S. J., and Lucas, A (2013) Generalized autoregressive score models with applications0.51121100%
8Harvey, A. C (2013) Dynamic Models for Volatility and Heavy Tails: With Applications to Financial and Economic Time Series0.51121100%
9Masreliez, C. J (1975) Approximate non-Gaussian filtering with linear state and observation relations0.51121100%
10West, M. and Harrison, J (1989) Bayesian Forecasting and Dynamic Models0.51121100%

Showing the top 10 of 28 scored citations.