This paper proposes a class of asymmetric Autoregressive Conditional Duration models, which extends the ACD model of Engle and Russell (1997). The asymmetry consists of letting the duration process depend on the state of the price process in the beginning and at the end of the each duration. If...

This paper introduces the logarithmic autoregressive conditional duration model (log-ACD model). The logarithmic version allows for more flexibilitythan the ACD model of Engel and Russel (1995), when additional variables are included in the model. We apply the log-ACD model to bid/ask prices...