Weak identification of long memory with implications for inference

• Main Authors: LI, Jia, PHILLIPS, Peter C. B., SHI, Shuping, Jun YU
• Format: text
• Language: English
• Published: Institutional Knowledge at Singapore Management University 2022
• Subjects: Realized volatility; Weak identification; Disjoint confidence sets; Trading volume; Long memory; Econometrics; Economic Theory
• Online Access: https://ink.library.smu.edu.sg/soe_research/2616; https://ink.library.smu.edu.sg/context/soe_research/article/3615/viewcontent/WeakIDFAR.pdf
• Institution: Singapore Management University

This paper explores weak identification issues arising in commonly used models of economic and financial time series. Two highly popular configurations are shown to be asymptotically observationally equivalent: one with long memory and weak autoregressive dynamics, the other with antipersistent shocks and a near-unit autoregressive root. We develop a data-driven semiparametric and identification-robust approach to inference that reveals such ambiguities and documents the prevalence of weak identification in many realized volatility and trading volume series. The identification-robust empirical evidence generally favors long memory dynamics in volatility and volume, a conclusion that is corroborated using social-media news flow data.