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EXTENSIONS OF THE STANDARDIZED CROSS‐SECTIONAL APPROACH TO SHORT‐HORIZON EVENT STUDIES
Author(s) -
Bremer Ronald,
Zhang Zhaohui
Publication year - 2007
Publication title -
journal of financial research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.319
H-Index - 49
eISSN - 1475-6803
pISSN - 0270-2592
DOI - 10.1111/j.1475-6803.2007.00225.x
Subject(s) - volatility (finance) , econometrics , event study , event (particle physics) , autoregressive conditional heteroskedasticity , economics , statistics , mathematics , history , context (archaeology) , physics , archaeology , quantum mechanics
Strong evidence indicates that short‐horizon event‐induced abnormal returns and volatility vary significantly over event days. Event‐study methods that assume constant event‐induced abnormal returns and volatility over event days have potentially inflated Type I error rates and poor test power. Our simple extensions of the Boehmer, Musumeci, and Poulsen (1991) approach scale abnormal returns with conditional variance, which is estimated with GARCH(1,1) and an indicator of the event in a two‐stage estimation. Our method improves the Boehmer, Musumeci, and Poulsen approach on model specification and test power, even under challenging event‐induced mean and volatility structures, and could standardize short‐horizon event studies.