While the development of Markov switching extensions to time series mo
deling has provided a useful way of characterizing business cycle dyna
mics, these models are not without their weaknesses. One problem is po
sed by the fact that since the state space for the unobserved state va
riables grows with the sample size, sampling distributions for maximum
-likelihood estimates are difficult to establish. A second problem is
that since the transition probabilities are constant, the conditional
expected duration of a phase is constant. This paper extends the model
so that the information contained in leading indicator data can be us
ed to forecast transition probabilities. These transition probabilitie
s can then be used to calculate expected durations. The model is appli
ed to US data to evaluate its ability to explain observed business cyc
le durations. The technical problems encountered with classical techni
ques are avoided by using Bayesian methods. Gibbs sampling techniques
are used to calculate expected posterior durations. (C) 1998 Elsevier
Science S.A. All rights reserved.