Author(s): Costa, Maria da Conceição ; Scotto, Manuel Gonzaléz ; Pereira, Isabel
Date: 2016
Persistent ID: http://hdl.handle.net/10773/16620
Origin: RIA - Repositório Institucional da Universidade de Aveiro
Subject(s): Asymmetric volatility; Ergodicity; Heteroscedasticity; Nonlinear time series; Overdispersion; Stationarity
The Asymmetric Power ARCH representation for the volatility was introduced by Ding et al. [3] in order to account for asymmetric responses in the volatility in the analysis of continuous-valued nancial time series like, for instance, the log-return series of foreign exchange rates, stock indices or share prices. As reported by Br ann as and Quoreshi [1], asymmetric responses in volatility are also observed in time series of counts such as the number of intra-day transactions in stocks. In this work, an asymmetric power autoregressive conditional Poisson model is introduced for the analysis of time series of counts exhibiting asymmetric overdispersion. Basic probabilistic and statistical properties are summarized and parameter estimation is discussed. A simulation study is presented to illustrate the proposed model. Finally, an empirical application to a set of data concerning the daily number of stock transactions is also presented to attest for its practical applicability in data analysis.
