We propose a new class of observation driven time series models referred to as Generalized Autoregressive Score (GAS) models. The driving mechanism of the GAS model is the scaled score of the likelihood function. This approach provides a unified and consistent framework for introducing...

We propose a new class of observation driven time series models referred to as Generalized Autoregressive Score (GAS) models. The driving mechanism of the GAS model is the scaled score of the likelihood function. This approach provides a unified and consistent framework for introducing...

We estimate a general microstructure model of the transitory and permanent impact of order flow on stock prices. Jumps are detected in both the transaction price (observation equation) and fundamental value (state equation). The model's parameters and variances are updated in real time. Prices...

This paper generalizes the ACD models of Engle and Russell (1998) using the so-called q-Weibull distribution as the conditional distribution. The new specification allows the hazard function to be non-monotonic. We document that the q-Weibull distribution recently suggested in physics as a...

A common practice in modeling intertrade durations is to use various hazard functions for data fitting. This paper calls into question this practice and suggests mixing the hazard function as exponential. An underlying hypothesis of the suggestion is that duration data have a mixture of...

We develop a Markov-Switching Autoregressive Conditional Intensity (MS-ACI) model with time-varying transitional parameters, and show that it can be reliably estimated via the Stochastic Approximation Expectation-Maximization algorithm. Applying our model to high-frequency transaction data, we...

In finance, durations between successive transactions are usually modelled by the autoregressive conditional duration model based on a continuous distribution omitting frequent zero values. Zero durations can be caused by either split transactions or independent transactions. We propose a...

In this paper, we suggest and evaluate specification tests to test the validity of the conditional mean function implied by Autoregressive Conditional Duration (ACD) models. We propose Lagrange multiplier tests against sign bias alternatives, various types of conditional moment tests and...

Likelihood based inference for multi-state latent factor intensity models is hindered by the fact that exact closed-form expressions for the implied data density are not available. This is a common and well-known problem for most parameter driven dynamic econometric models. This paper reviews,...

Likelihood based inference for multi-state latent factor intensity models is hindered by the fact that exact closed-form expressions for the implied data density are not available. This is a common and well-known problem for most parameter driven dynamic econometric models. This paper reviews,...