Preprint
Fixed-order PCA: Theory for Overestimated Factor Models
ArXiv.org
Cornell University
05/18/2026
DOI: 10.48550/arxiv.2605.18448
Abstract
We develop asymptotic theory for principal component analysis (PCA) of a high-dimensional factor model in which the working dimensionRis fixed and only required to satisfyR ≥ r , whereris the true number of factors. Building on anisotropic local laws from random matrix theory, we show that the ``extra'' empirical eigencomponents beyond ther -th are asymptotically noise-governed, incoherent, and nearly orthogonal to the factor loadings. We introduce two rotations, an expandedr× RmapH'and a compressedR× rmapH⁺ , and establish consistency of the estimated factors under both. As an application, we analyze a factor-augmented regression for treatment-effect inference and prove√T̅ -asymptotic normality for every fixedR ≥ 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 boundingrfrom above.
Details
- Title: Subtitle
- Fixed-order PCA: Theory for Overestimated Factor Models
- Creators
- Yuan Liao - University of IowaXin Tong - National University of SingaporeWanjie Wang - National University of SingaporeDacheng Xiu - University of Chicago
- Resource Type
- Preprint
- Publication Details
- ArXiv.org
- DOI
- 10.48550/arxiv.2605.18448
- ISSN
- 2331-8422
- Publisher
- Cornell University; Ithaca, New York
- Language
- English
- Date posted
- 05/18/2026
- Academic Unit
- Economics
- Record Identifier
- 9985164631002771
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