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Fixed-order PCA: Theory for Overestimated Factor Models

Yuan Liao, Xin Tong, Wanjie Wang, Dacheng Xiu

arXiv 18 May 2026 · Mathematics — Statistics Theory

arXiv:2605.18448 · PDF · DOI · OpenAlex · Extracted main text

Abstract

We develop asymptotic theory for principal component analysis (PCA) of a high-dimensional factor model in which the working dimension $R$ is fixed and only required to satisfy $R \ge r$, where $r$ is the true number of factors. Building on anisotropic local laws from random matrix theory, we show that the “extra” empirical eigencomponents beyond the $r$-th are asymptotically noise-governed, incoherent, and nearly orthogonal to the factor loadings. We introduce two rotations, an expanded $r\times R$ map $H'$ and a compressed $R\times r$ map $H^{+}$, and establish consistency of the estimated factors under both. As an application, we analyze a factor-augmented regression for treatment-effect inference and prove $\sqrt{T}$-asymptotic normality for every fixed $R \ge r$. These results provide a theoretical underpinning for the common empirical practice of adopting a conservative upper bound on the number of factors, and shift the analytical burden from consistent dimension selection to the milder requirement of bounding $r$ from above.

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37
references
71
in-text mentions
37
distinct cited
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self-citations
11,361
main-text words

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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
1Bai, J (2003) Inferential theory for factor models of large dimensions1.00063100%
2Knowles, Antti and Yin, Jun (2017) Anisotropic local laws for random matrices0.76318544%
3Moon, R. and Weidner, M (2015) Linear regression for panel with unknown number of factors as interactive fixed effects0.73732100%
4Abbe, Emmanuel and Fan, Jianqing and Wang, Kaizheng and Zhong, Yiqiao (2020) Entrywise eigenvector analysis of random matrices with low expected rank0.64422100%
5Belloni, Alexandre and Chernozhukov, Victor and Hansen, Christian (2014) Inference on treatment effects after selection among high-dimensional controls0.64422100%
6Chernozhukov, Victor and Chetverikov, Denis and Demirer, Mert and Du… (2016) Double machine learning for treatment and causal parameters0.64422100%
7Fan, Jianqing and Wang, Weichen and Zhong, Yiqiao (2018) An $ _infty$ eigenvector perturbation bound and its application to robust covariance estimation self0.64422100%
8Fan, Jianqing and Li, Kunpeng and Liao, Yuan (2021) Recent developments in factor models and applications in econometric learning self0.5112250%
9Bai, J. and Ng, S (2002) Determining the number of factors in approximate factor models0.51121100%
10French, Eric and Jones, John Bailey (2011) The effects of health insurance and self-insurance on retirement behavior0.51121100%

Showing the top 10 of 37 scored citations.