Network effects of the productivity of infrastructure in developing countries

Using panel data models, the author examines the threshold effects of the productivity of infrastructure investment in developing countries. He considers various specifications of an augmented production function that allow for endogenous thresholds. More precisely, these specifications are tested in a panel threshold regression model. The author's main robust result is the presence of strong threshold effects in the relationship between output and private and public inputs. Whatever the transition mechanism used, the testing procedures lead to strong rejection of the linearity of this relationship. In particular, the productivity of infrastructure investment generally exhibits some network effects. When the available stock of infrastructure is very low, investment in this sector has the same productivity as noninfrastructure investment. On the contrary, when a minimum network is available, the marginal productivity of infrastructure investment is generally largely greater than the productivity of other investment. Finally, when the main network is achieved, its marginal productivity becomes similar to the productivity of other investment.Economic Theory&Research,Investment and Investment Climate,Public Sector Economics&Finance,Non Bank Financial Institutions,Technology Industry

Resource Usage Protocols for Iterators

We discuss usage protocols for iterator objects that prevent concurrent modifications of the underlying collection while iterators are in progress. We formalize these protocols in Java-like object interfaces, enriched with separation logic contracts. We present examples of iterator clients and proofs that they adhere to the iterator protocol, as well as examples of iterator implementations and proofs that they implement the iterator interface

Credit Market Disequilibrium in Poland: Can We Find What We Expect? Non-Stationarity and the “Min”Condition

This paper presents an empirical investigation of the disequilibrium hypothesis on the Polish loan market in the 1990s. Using data over this period of deep transition, we estimate a disequilibrium model with a standard maximum likelihood method. However, the estimates are highly counter-intuitive as regards the timing of the identified regimes. We show that the gap between the econometric evidence and the expected results may stem from the issue of stochastic non-stationarity in a disequilibrium setting based on the “min” condition. We find that the omission of one non-stationary variable of the cointegrating space or the absence of a “structural” cointegrating relationship in one or both regimes lead to a spurious configuration. In such a case, using, wrongly, the standard likelihood function, derived under the hypothesis of stationarity, may lead to non-convergent estimates of structural parameters and, as a consequence, to a fallacious regimes identification. Therefore, as the first approach to this issue, we estimate a disequilibrium model with stationary data. The empirical results are then robust and economically founded and correspond to the set and the timing of anticipated regimes.monetary standard and regimes, non-stationarity and cointegration, transition, Poland.

Backtesting VaR Accuracy: A New Simple Test

This paper proposes a new test of Value at Risk (VaR) validation. Our test exploits the idea that the sequence of VaR violations (Hit function) - taking value 1-α, if there is a violation, and -α otherwise - for a nominal coverage rate α verifies the properties of a martingale difference if the model used to quantify risk is adequate (Berkowitz et al., 2005). More precisely, we use the Multivariate Portmanteau statistic of Li and McLeod (1981) - extension to the multivariate framework of the test of Box and Pierce (1970) - to jointly test the absence of autocorrelation in the vector of Hit sequences for various coverage rates considered as relevant for the management of extreme risks. We show that this shift to a multivariate dimension appreciably improves the power properties of the VaR validation test for reasonable sample sizes.Value-at-Risk; Risk Management; Model Selection

Are Public Investment Efficient in Creating Capital Stocks in Developing Countries?

In many poor countries, the problem is not that governments do not invest, but that these investments do not create productive capital. So, the cost of public investments does not correspond to the value of the capital stocks. In this paper, we propose an original non parametric approach to evaluate the efficiency function that links variations (net of depreciation) of stocks to public investments. We consider four sectors (electricity, telecommunications, roads and railways) of two Latin American countries (Mexico and Colombia). We show that there is a large discrepancy between the amount of investments and the value of increases in stocks.Public Capital | Capital Stocks | Developing Countries

Are Public Investment Efficient in Creating Capital Stock in Developing Countries?.

In many poor countries, the problem is not that governments do not invest, but that these investments do not create productive capital. So, the cost of public investments does not correspond to the value of the capital stocks. In this paper, we propose an original non parametric approach to evaluate the efficiency function that links variations (net of depreciation) of stocks to public investments. We consider four sectors (electricity, telecommunications, roads and railways) of two Latin American countries (Mexico and Colombia). We show that there is a large discrepancy between the amount of investments and the value of increases in stocks.Developing Countries; Capital Stocks; Public Capital;

Permission-Based Separation Logic for Multithreaded Java Programs

This paper motivates and presents a program logic for reasoning about multithreaded Java-like programs with concurrency primitives such as dynamic thread creation, thread joining and reentrant object monitors. The logic is based on concurrent separation logic. It is the first detailed adaptation of concurrent separation logic to a multithreaded Java-like language. The program logic associates a unique static access permission with each heap location, ensuring exclusive write accesses and ruling out data races. Concurrent reads are supported through fractional permissions. Permissions can be transferred between threads upon thread starting, thread joining, initial monitor entrancies and final monitor exits.\ud This paper presents the basic principles to reason about thread creation and thread joining. It finishes with an outlook how this logic will evolve into a full-fledged verification technique for Java (and possibly other multithreaded languages)

What would Nelson and Plosser find had they used panel unit root tests?

In this study, we systemically apply nine recent panel unit root tests to the same fourteen macroeconomic and financial series as those considered in the seminal paper by Nelson and Plosser (1982). The data cover OECD countries from 1950 to 2003. Our results clearly point out the difficulty that applied econometricians would face when they want to get a simple and clear-cut diagnosis with panel unit root tests. We confirm the fact that panel methods must be very carefully used for testing unit roots in macroeconomic or financial panels. More precisely, we find mitigated results under the cross-sectional independence assumption, since the unit root hypothesis is rejected for many macroeconomic variables. When international cross-correlations are taken into account, conclusions depend on the specification of these cross-sectional dependencies. Two groups of tests can be distinguished. The first group tests are based on a dynamic factor structure or an error component model. In this case, the non stationarity of common factors (international business cycles or growth trends) is not rejected, but the results are less clear with respect to idiosyncratic components. The second group tests are based on more general specifications. Their results are globally more favourable to the unit root assumption.Panel Unit Root Tests

Credit Market Disequilibrium in Poland: Can We Find What We Expect? Non-Stationarity and the “Min”Condition

This paper presents an empirical investigation of the disequilibrium hypothesis on the Polish loan market in the 1990s. Using data over this period of deep transition, we estimate a disequilibrium model with a standard maximum likelihood method. However, the estimates are highly counter-intuitive as regards the timing of the identified regimes. We show that the gap between the econometric evidence and the expected results may stem from the issue of stochastic non-stationarity in a disequilibrium setting based on the “min” condition. We find that the omission of one non-stationary variable of the cointegrating space or the absence of a “structural” cointegrating relationship in one or both regimes lead to a spurious configuration. In such a case, using, wrongly, the standard likelihood function, derived under the hypothesis of stationarity, may lead to non-convergent estimates of structural parameters and, as a consequence, to a fallacious regimes identification. Therefore, as the first approach to this issue, we estimate a disequilibrium model with stationary data. The empirical results are then robust and economically founded and correspond to the set and the timing of anticipated regimes.http://deepblue.lib.umich.edu/bitstream/2027.42/39967/3/wp581.pd

The Feldstein-Horioka Puzzle: a Panel SmoothTransition Regression Approach

This paper proposes an original framework to determine the relative influence of fivefactors on the Feldstein and Horioka result of OECD countries with a strong saving-investment association. Based on panel threshold regression models, we establishcountry-specific and time-specific saving retention coefficients for 24 OECD coun-tries over the period 1960-2000. These coefficients are assumed to change smoothly,as a function of five threshold variables, considered as the most important in theliterature devoted to the Feldstein and Horioka puzzle. The results show that; de-gree of openness, country size and current account to GDP ratios have the greatestinfluence on the investment-saving relationship.Feldstein Horioka puzzle, Panel Smooth Threshold Regression models,saving-investment association, capital mobility .