Haroon Mumtaz

PPP Strikes Back: Aggregation And the Real Exchange Rate

Internet, voice calls, and messaging services have become ubiquitous and the means by which the services are accessed varies widely. The number and types of devices that may use these services have also proliferated. To serve a number and variety of client devices, a mobile Hotspot may be used, which is a device that may include a modem for mobile broadband access and a short range wireless link to distribute the services to local devices which may have such connectivity. Power consumption of battery powered client devices is an important consideration. A method and apparatus are disclosed that enable a client device to receive paging information from the mobile networks through a mobile Hotspot over a short range wireless link which may reduce power consumption of client devices.

Assessing the Economy-Wide Effects of Quantitative Easing

This paper examines the macroeconomic impact of the first round of quantitative easing (QE) by the Bank of England which started in March 2009. Although Bank Rate, the UK policy rate, was reduced to ½%, effectively its lower bound, the Bank’s Monetary Policy Committee felt that additional measures were necessary to meet the inflation target in the medium term. The policy of QE entailed buying private and mainly public assets in large quantities using central bank money, with the aim of injecting money into the economy and boosting nominal spending, in order to help achieve the Bank’s inflation target. Over the period from March 2009 to January 2010, the Bank of England purchased £200 billion of assets, mainly consisting of government securities. We attempt to quantify the effects of these purchases by focusing on the impact of lower long-term interest rates on the wider economy. This is motivated by empirical evidence indicating that QE purchases reduced long-term UK government bond yields by about 100 basis points. Other transmission channels are also possible, but are not considered in this paper. We use three different models to conduct counterfactual simulations to estimate the impact of QE on output and inflation: a large Bayesian VAR; a change-point structural VAR; and a time-varying parameter VAR. Our preferred average estimates from the three models suggest that QE may have had a peak effect on the level of real GDP of around 1½% and a peak effect on annual CPI inflation of about 1¼ percentage points. These estimates are shown to vary considerably across the different model specifications, and with the precise assumptions made to generate the counterfactual simulations, and are therefore subject to considerable uncertainty.

The Changing Transmission of Uncertainty shocks in the US: An Empirical Analysis

This article investigates if the impact of uncertainty shocks on the U.S. economy has changed over time. To this end, we develop an extended factor augmented vector autoregression (VAR) model that simultaneously allows the estimation of a measure of uncertainty and its time-varying impact on a range of variables. We find that the impact of uncertainty shocks on real activity and financial variables has declined systematically over time. In contrast, the response of inflation and the short-term interest rate to this shock has remained fairly stable. Simulations from a nonlinear dynamic stochastic general equilibrium (DSGE) model suggest that these empirical results are consistent with an increase in the monetary authorities’ antiinflation stance and a “flattening” of the Phillips curve. Supplementary materials for this article are available online.

Changes in the Transmission of Monetary Policy: Evidence from a Time-Varying Factor-Augmented VAR

This paper re-examines the evolution of the US monetary transmission mechanism using an empirical framework that incorporates substantially more information than the standard tri-variate VAR model used in most previous studies. In particular, we employ an extended version of a factor-augmented VAR, where we introduce time variation in the coefficients and stochastic volatilities in the variances of the shocks. Our formulation has two substantive advantages over earlier work: (i) the additional information summarised by the common factors that are extracted from a large panel of aggregate and disaggregate variables improves the identification of the monetary policy shocks since the factors capture more accurately the amount of information analysed by the monetary authority, (ii) we are able to estimate the time-varying effects of monetary policy surprises on macroeconomic aggregates and disaggregate prices and quantities of personal consumption expenditures. Our main results indicate that time variation is a dominant feature of key macroeconomic variables and their components. In analysing the temporal evolution of disaggregate dynamics, we uncover a considerable amount of heterogeneity in sectoral price responses which suggests that monetary policy actions exert an important, and potentially long-lasting, influence on relative prices in the US economy.

Evolving International Inflation Dynamics: Evidence from a Time-varying Dynamic Factor Model

Several industrialised countries have had a similar inflation experience in the past 30 years, with inflation high and volatile in the 1970s and the 1980s but low and stable in the most recent period. We explore the dynamics of inflation in these countries via a time-varying factor model. This statistical model is used to describe movements in inflation that are idiosyncratic or country specific and those that are common across countries. In addition, we investigate how comovement has varied across the sample period. Our results indicate that there has been a decline in the level, persistence and volatility of inflation across our sample of industrialised countries. In addition, there has been a change in the degree of comovement, with the level and persistence of national inflation rates moving more closely together since the mid-1980s.

Exchange Rate Pass-Through into UK Import Prices

In this paper we estimate the rate of exchange rate pass-through (ERPT) into UK import prices using disaggregate data at the SITC-2 and SITC-3 digit level. Consistent with earlier studies, we find evidence for significant heterogeneity among the estimated industry-specific pass-through rates. In an environment where cross-sectional heterogeneity is significant the use of aggregate data can be misleading since aggregation may lead to heavily biased ERPT estimates at the economy-wide level. We demonstrate that the aggregation bias caused by this heterogeneity is not negligible for the UK data. Further, we investigate the source of the cross-sectional variation in the estimated industry-specific pass-through rates. For our sample, we find the industry-specific average inflation rates to be significant in explaining this variation. Furthermore, we find evidence for short-run and long-run partial pass-through into food and manufacturing sectors. As for the economy-wide ERPT the conclusion stands, possibly reflecting the relatively large weight of manufacturing goods in UK imports. Finally, we find a significant reduction in estimated ERPT rates since 1995 caused by increased stability of the UK economy over the past decade.

International Transmission of Shocks: A Time-Varying Factor-Augmented VAR Approach to the Open Economy

A growing literature has documented changes to the dynamics of key macroeconomic variables in industrialized countries and highlighted the possibility that these variables may react differently to structural shocks over time. However, existing empirical work on the international transmission of shocks largely abstracts from the possibility of changes to the international transmission mechanism across time. In addition, the literature has largely employed small-scale models with limited number of variables. This paper introduces an empirical model which allows the estimation of time-varying response of a large set of domestic variables to foreign money supply, demand and supply shocks. The key results show that a foreign monetary policy tightening resembles the classic beggar-thy-neighbour scenario for the United Kingdom in the period 1975-90. In more recent periods, the response is negative but largely insignificant.

EXCESS SENSITIVITY, LIQUIDITY CONSTRAINTS, AND THE COLLATERAL ROLE OF HOUSING

We estimate consumption Euler equations using U.K. household-level data, employing a switching regression technique. We find excess sensitivity to income for one group of households but not for a second group. The likelihood of excess sensitivity is greater for the young, those without liquid assets, the degree-educated, ethnic minorities and those with negative home equity, consistent with liquidity constraints and buffer-stock saving. Housing capital gains affect the consumption plans of the excess sensitivity group of households, but not the other group. These results are consistent with a “collateral channel†for housing. Around 20%–40% of U.K. households display excess sensitivity.

Investigating the Structural Stability of the Phillips Curve Relationship

The reduced-form correlation between inflation and measures of real activity has changed substantially for the main developed economies over the post-WWII period. In this paper we attempt to describe the observed inflation dynamics in the United Kingdom, the United States and the euro area with a sequence of New Keynesian Phillips Curve (NKPC) equations that are log-linearised around different, non-zero, steady-state inflation levels. In doing this, we follow a two-step estimation strategy. First, we model the time variation in the relationship between inflation and a real cost-based measure of activity through a Markov-switching vector autoregressive model. We then impose the cross-equation restrictions of a Calvo pricing-based NKPC under non-zero steady-state inflation and estimate the structural parameters by minimising for each inflation state the distance between the restricted and unrestricted vector autoregressive parameters. The structural estimation results indicate that for all the economies there is evidence for a structurally invariant NKPC, albeit with a significant backward-looking component.

What Lies Beneath? A Time‐Varying Favar Model for the UK Transmission Mechanism

This paper uses a time-varying Factor Augmented VAR to investigate the evolving transmission of monetary policy and demand shocks in the UK. Simultaneous estimation of time-varying impulse responses of a large set of macroeconomic variables and disaggregated prices suggest that the response of inflation, money supply and asset prices to monetary policy and demand shocks has changed over the sample period. In particular, during the post-1992 inflation targeting period, monetary policy shocks started having a bigger impact on prices, a smaller impact on activity and began contributing more to overall volatility. In contrast, demand shocks had the largest impact on these variables before the 1990s. We also document changes in the response of disaggregated prices, with the median reaction to contractionary policy shocks becoming more negative and the distribution more dispersed post-1992. JEL Classification: C38, E44, E52