Optimality conditions¶and bubbles in sequential economies¶and bounded relative risk-aversion

We provide specific qualifications in order that Kuhn–Tucker type Euler equations and transversality conditions at infinity hold in stochastic equilibrium models with heterogeneous agents and where assets are traded in sequential markets. It is not assumed that uncertainty is modeled as an event-tree structure or that preferences are necessarily bounded. We also describe an important class of preferences based on bounded relative risk aversion which yields relevant simplifications. Our results are used to establish conditions that rule out asset pricing bubbles. Specific examples of economies with bubbles are also discussed. Received: 28 January 2002 / Accepted: 19 July 2002 We are grateful to the editor and an anonymous referee for their valuable comments. This research was partially supported by MURST (Italy), National Group on “Nonlinear Dynamics and Stochastic Models in Economics and Finance”.     

Are stationarity and cointegration restrictions really necessary for the intertemporal budget constraint?

Time series related to fiscal and external deficits are commonly subjected to stationarity and cointegration tests to assess if the deficits are sustainable. Such tests are incapable of rejecting sustainability. The intertemporal budget constraint proves to be satisfied if either the debt series or the revenue and with-interest spending series are integrated of arbitrarily high order, i.e., stationary after differencing arbitrarily often. Revenues and spending do not have to be cointegrated. Rejections of low-order difference-stationarity and of cointegration are thus consistent with the intertemporal budget constraint. Error-correction-type policy reaction functions are suggested as more promising for understanding deficit problems.     

MEASURING THE OPERATIONAL EFFICIENCY OF COMMERCIAL BANKS IN NAMIBIA

This paper examines the efficiency of commercial banks in Namibia using the standard econometric frontier approach. Although two aspects of efficiency (scale and scope) receive our attention, the emphasis is on the latter which pertains to whether a firm produces as efficiently as it possibly can, given its size. Our results indicate that substantial economies of scale exist in commercial banking in Namibia. This will tend to suggest that commercial banks in Namibia can increase their efficiency by increasing their current scale of operation. The results for scope economies show that the current level of input combination does not make for maximum efficiency as sufficient scope exists for a more efficient combination of inputs. We believe this will reduce operating costs in the industry and stimulate efficiency.     

Intertemporal substitution and the liquidity effect in a sticky price model

The liquidity effect, defined as a decrease in nominal interest rates in response to a monetary expansion, is a major stylized fact of the business cycle. This paper first confirms that, with separable preferences, a low degree of intertemporal substitution in consumption is a necessary condition for the existence of the liquidity effect. In contrast to this result, in a model with non-separable preferences and capital accumulation it takes an implausibly high elasticity of intertemporal substitution to produce a liquidity effect. The robustness of these results to alternative degrees of nominal rigidities, capital adjustment costs and stochastic monetary processes is also analysed. We conclude that price stickiness, by itself, does not guarantee the existence of a liquidity effect.     

Interest rate corridors and reserves

This paper evaluates reserves regimes versus interest rate corridors, which have become competing frameworks for monetary policy implementation. Rate corridors, relying on lending and deposit facilities to create ceilings and floors for overnight interest rates, evince mixed results on controlling volatility. Reserve requirements allow period-average smoothing of interest rates but, even if remunerated, are subject to reserve avoidance activities. A system of voluntary, period-average reserve commitments could offer equivalent rate-smoothing advantages. If central banks created symmetric opportunity costs of meeting or falling short of period-average reserve requirements (or commitments), they could achieve flat reserve demand on settlement day.     

The future of social security

We analyze the effect of the projected demographic transition on the political support for social security, and equilibrium outcomes. Embedding a probabilistic-voting setup of electoral competition in the standard OLG model with capital accumulation, we find that intergenerational transfers arise in the absence of altruism, commitment, or trigger strategies. Closed-form solutions predict population ageing to lead to higher social security tax rates, a rising share of pensions in GDP, but eventually lower social security benefits per retiree. The response of equilibrium tax rates to demographic shocks reduces old-age consumption risk. Calibrated to match features of the U.S. economy, the model suggests that, in response to the projected demographic transition, social security tax rates will gradually increase to 16%. Other policies that distort labor supply will become less important; labor supply therefore will rise, in contrast with frequently voiced fears.     

Some Evidence on the Adjustment of Producer Prices*

We document producer price adjustment using a low‐inflation micro price dataset. On average 24% of prices adjust each month, with an average increase/decrease of 6%. Producer prices adjust more frequently than consumer prices, but their size of adjustment is typically smaller. Sectoral heterogeneity in the frequency of price adjustment is strongly related to heterogeneity in the cost structure. Fluctuations in aggregate producer price inflation occur to a large extent through variation in the relative share of upward and downward price adjustment.     

What motivates a subprime borrower to default?

This paper uses a real options approach to analyse the exercise of the default option embedded in mortgages. In particular, it examines a subprime household who borrows at a premium, but hopes to refinance at prime rates if their house appreciates. We show how these optimal default decisions can be used to calculate probabilities of default – an important input for risk management and pricing purposes. Numerical examples are provided, calibrated to US data. In a low interest rate environment, the credit-upgrade potential may discourage subprime borrowers from defaulting. However, default probabilities are highly sensitive to changes in interest rates and house prices. This provides a rational explanation for the prevalence of adjustable rate mortgages among subprime borrowers, and the subsequent large numbers of defaults, when interest rates rose and house prices declined.     

THE CHANGING VOLATILITY OF THE SOUTH AFRICAN ECONOMY

During the last decade economic literature explored the presence of and reasons for what became known as “the great moderation” in the US and other G7 countries. “The great moderation” describes the decrease in economic volatility experienced in many of the G7 countries. This paper finds that in South Africa volatility is also not constant (it even finds that there are autoregressive conditional heteroskedastic effects present) and that volatility also decreased, particularly since 1994. Following the literature, the paper explores several reasons for this decrease and finds that smaller shocks, better monetary policy and improvements in the financial sector that place less liquidity constraints on individuals and allow them to manage their debt better are some of the main reasons for the reduction in the volatility of the South African economy. The literature on the G7 also suggests that better inventory management contributed to the lower volatility. However, this seems not to be true for South Africa.     

Inflation dynamics: A cross-country investigation

We document that “persistent and lagged” inflation (with respect to output) is a world-wide phenomenon in that these short-run inflation dynamics are highly synchronized across countries. In particular, the average cross-country correlation of inflation is significantly and systematically stronger than that of output, while the cross-country correlation of money growth is essentially zero. We investigate whether standard monetary models driven by monetary shocks are consistent with the empirical facts. We find that neither the new Keynesian sticky-price model nor the sticky-information model can fully explain the data. An independent contribution of the paper is to provide a simple solution technique for solving general equilibrium models with sticky information.