Prior elicitation in multiple change-point models

This paper discusses Bayesian inference in change-point models. Existing approaches involve placing a (possibly hierarchical) prior over a known number of change-points. We show how two popular priors have some potentially undesirable properties (e.g. allocating excessive prior weight to change-points near the end of the sample) and discuss how these properties relate to imposing a fixed number of changepoints in-sample. We develop a new hierarchical approach which allows some of of change-points to occur out-of sample. We show that this prior has desirable properties and handles the case where the number of change-points is unknown. Our hierarchical approach can be shown to nest a wide variety of change-point models, from timevarying parameter models to those with few (or no) breaks. Since our prior is hierarchical, data-based learning about the parameter which controls this variety occurs

Are apparent findings of nonlinearity due to structural instability in economic time series?

Many modelling issues and policy debates in macroeconomics depend on whether macroeconomic times series are best characterized as linear or nonlinear. If departures from linearity exist, it is important to know whether these are endogenously generated (as in, e.g., a threshold autoregressive model) or whether they merely reflect changing structure over time. We advocate a Bayesian approach and show how such an approach can be implemented in practice. An empirical exercise involving several macroeconomic time series shows that apparent findings of threshold type nonlinearities could be due to structural instability

Prior Elicitation in Multiple Change-point Models

This paper discusses Bayesian inference in change-point models. The main existing approaches either attempt to be noninformative by using a Uniform prior over change-points or use an informative hierarchical prior. Both these approaches assume a known number ofchange-points. We show how they have some potentially undesirable properties and discuss how these properties relate to the imposition of a …xed number of changepoints. We develop a new Uniform prior which allows some of the change-points to occur out-of sample. This prior has desirable properties, can reasonably be interpreted as “noninformative” and handles the case where the number of change-points is unknown. We show how the general ideas of our approach can be extended to informative hierarchical priors. With arti…cial data and two empirical illustrations, we show how these di¤erent priors can have a substantial impact on estimation and prediction even with moderately large data sets.

The dynamics of UK and US inflation expectations

This paper investigates the relationship between short term and long term inflation expectations in the US and the UK with a focus on inflation pass through (i.e. how changes in short term expectations affect long term expectations). An econometric methodology is used which allows us to uncover the relationship between inflation pass through and various explanatory variables. We relate our empirical results to theoretical models of anchored, contained and unmoored inflation expectations. For neither country do we find anchored or unmoored inflation expectations. For the US, contained inflation expectations are found. For the UK, our findings are not consistent with the specific model of contained inflation expectations presented here, but are consistent with a more broad view of expectations being constrained by the existence of an inflation target

Liquidity effects of the events of September 11, 2001

Banks rely heavily on incoming payments from other banks to fund their own payments. The terrorist attacks of September 11, 2001, destroyed facilities in Lower Manhattan, leaving some banks unable to send payments through the Federal Reserve's Fedwire payments system. As a result, many banks received fewer payments than expected, causing unexpected shortfalls in banks' liquidity. These disruptions also made it harder for banks to redistribute balances across the banking system in a timely manner. In this article, the authors measure the payments responses of banks to the receipt of payments from other banks, both under normal circumstances and during the days following the attacks. Their analysis suggests that the significant injections of liquidity by the Federal Reserve, first through the discount window and later through open market operations, were important in allowing banks to reestablish their normal patterns of payments coordination.Fedwire ; Electronic funds transfers ; War - Economic aspects ; Bank liquidity ; Payment systems

Understanding Liquidity and Credit Risks in the Financial Crisis

This paper develops a structured dynamic factor model for the spreads between London Interbank Offered Rate (LIBOR) and overnight index swap (OIS) rates for a panel of banks. Our model involves latent factors which reflect liquidity and credit risk. Our empirical results show that surges in the short term LIBOR-OIS spreads during the 2007-2009 fi…nancial crisis were largely driven by liquidity risk. However, credit risk played a more signi…cant role in the longer term (twelve-month) LIBOR-OIS spread. The liquidity risk factors are more volatile than the credit risk factor. Most of the familiar events in the fi…nancial crisis are linked more to movements in liquidity risk than credit risk.

The Dynamics of UK and US Inflation Expectations

This paper investigates the relationship between short term and long term inflation expectations in the US and the UK with a focus on inflation pass through (i.e. how changes in short term expecta tions affect long term expectations). An econometric methodology is used which allows us to uncover the relationship between inflation pass through and various explanatory variables. We relate our empirical results to theoretical models of anchored, contained and unmoored inflation expectations. For neither country do we …find anchored or unmoored inflation expectations. For the US, contained inflation expectations are found. For the UK, our fi…ndings are not consistent with the speci…c model of contained inflation expectations presented here, but are consistent with a broader view of expectations being constrained by the existence of an inflation target.

Re-examining the Consumption-Wealth Relationship: The Role of Model Uncertainty

This paper discusses the consumption-wealth relationship. Following the recent influential work of Lettau and Ludvigson [e.g. Lettau and Ludvigson (2001), (2004)], we use data on consumption, assets and labor income and a vector error correction framework. Key findings of their work are that consumption does respond to permanent changes in wealth in the expected manner, but that most changes in wealth are transitory and have no effect on consumption. We investigate the robustness of these results to model uncertainty and argue for the use of Bayesian model averaging. We find that there is model uncertainty with regards to the number of cointegrating vectors, the form of deterministic components, lag length and whether the cointegrating residuals affect consumption and income directly. Whether this uncertainty has important empirical implications depends on the researcher's attitude towards the economic theory used by Lettau and Ludvigson. If we work with their model, our findings are very similar to theirs. However, if we work with a broader set of models and let the data speak, we obtain somewhat different results. In the latter case, we find that the exact magnitude of the role of permanent shocks is hard to estimate precisely. Thus, although some support exists for the view that their role is small, we cannot rule out the possibility that they have a substantive role to play.wealth effect; vector error correction model; Bayesian model averaging; cointegration; variance decomposition.

A New Model of Trend Inflation

This paper introduces a new model of trend (or underlying) inflation. In contrast to many earlier approaches, which allow for trend inflation to evolve according to a random walk, ours is a bounded model which ensures that trend inflation is constrained to lie in an interval. The bounds of this interval can either be fixed or estimated from the data. Our model also allows for a time-varying degree of persistence in the transitory component of inflation. The bounds placed on trend inflation mean that standard econometric methods for estimating linear Gaussian state space models cannot be used and we develop a posterior simulation algorithm for estimating the bounded trend inflation model. In an empirical exercise with CPI inflation we find the model to work well, yielding more sensible measures of trend inflation and forecasting better than popular alternatives such as the unobserved components stochastic volatility model.