This paper proposes an asymmetric autoregressive conditional duration (ACD) model, which extends the ACD model of Engle and Russell (1998). The asymmetry consists of letting the duration process depend on the state of the price process. If the price has increased, the parameters of the ACD model...

This paper introduces the logarithmic autoregressive conditional duration (Log-ACD) model and compares it with the ACD model of Engle and Russell [1998]. The logarithmic version allows to introduce in the model additional variables without sign restrictions on their coefficients. We apply the...