Remaining life estimation of used components in consumer products: Life cycle data analysis by Weibull and artificial neural networks

Environmental awareness and legislative pressures have made manufacturers responsible for the take-back and end-of-life treatment of their products. To competitively exploit these products, one option is to incorporate used components in “new” or remanufactured products. However, this option is partly limited by a firm's ability to assess the reliability of used components. A comprehensive two-step approach is proposed. The first stage phase statistically analyzes the behavior of components for reuse. A well-known reliability assessment method, the Weibull analysis, is applied to the time-to-failure data to assess the mean life of components. In the second phase, the degradation and condition monitoring data are analyzed by developing an artificial neural network (ANN) model. The advantages of this approach over traditional approaches employing multiple regression analysis are highlighted with empirical data from a consumer product. Finally, the Weibull analysis and the ANN model are then integrated to assess the remaining useful life of components for reuse. This is a critical advance in sustainable management of supply chains since it allows for a better understanding of not only service requirements of product, but the remaining life in a product and hence its suitability for reuse or remanufacture. Future work should assess: (1) reduction in downtime of process equipment through the implementation of this technique as a means to better manage preventative maintenance; (2) reduce field failure of remanufactured product; (3) selling-service strategy through implementation of the proposed methodology.     

Simulation driven inferences for multiply imputed longitudinal datasets*

In this article, we demonstrate by simulations that rich imputation models for incomplete longitudinal datasets produce more calibrated estimates in terms of reduced bias and higher coverage rates without duly deflating the efficiency. We argue that the use of supplementary variables that are thought to be potential causes or correlates of missingness or outcomes in the imputation process may lead to better inferential results in comparison to simpler imputation models. The liberal use of these variables is recommended as opposed to the conservative strategy.     

Implementation of college admission rules

Summary We consider both Nash and strong Nash implementation of various matching rules for college admissions problems. We show that all such rules are supersolutions of the stable rule. Among these rules the lower bound stable rule is implementable in both senses. The upper bound Pareto and individually rational rule is strong Nash implementable yet it is not Nash implementable. Two corollaries of interest are the stable rule is the minimal (Nash or strong Nash) implementable solution that is Pareto optimal and individually rational, and the stable rule is the minimal (Nash or strong Nash) implementable extension of any of its subsolutions.We wish to thank Professor William Thomson for his efforts in supervision as well as his useful suggestions. We are grateful to the participants in his reading class, workshops at Bilkent University, University of Rochester, and in particular Jeffrey Banks, Stephen Ching, Bhaskar Dutta, Rangarajan Sundaram and an anonymous referee for their helpful comments.     

Determinants of cross-border merger premia

Firms have a broad range of rationales for engaging in cross-border mergers and other forms of foreign direct investment (FDI); while some companies are in search of the cost advantages provided by foreign resources, other firms are primarily interested in gaining access to new markets. Although a significant amount of research has explored the patterns of FDI, little work has been done to assess what influences the value of cross-border mergers and, in particular, what determines why some cross-border mergers are expected to result in higher synergies when compared to others. This paper explores what characteristics of a merger are expected to increase the synergies that a firm will accrue from a cross-border merger by testing how a variety of factors impact the premia paid to effectuate a cross-border merger. We find that firms are willing to pay a higher premium to obtain greater control over foreign firms, and that this control is even more important in mergers involving firms in emerging markets. We also find that the factors affecting deal premia in cross-border mergers differ based on whether the acquirer has a high or low intangible asset intensity level.     

The role of direct flights in trade costs

Effects of direct flights on trade costs are investigated using micro price data at the city level. After controlling for local retail/distribution costs, traded input prices are obtained to be further used in the measurement of trade costs across cities through arbitrage conditions. The existence of a direct flight enters trade costs regressions negatively and significantly. The results are shown to be robust to the consideration of many control variables, nonlinearities in the effects of distance on trade costs, possible endogeneity of having direct flights between cities and alternative definitions of the data. The direct flights that are shown to be determined by bilateral air services agreements are further shown to reduce trade costs through an endogeneity analysis; the main policy implications are twofold: (i) international trade policies through aviation services, such as Open Skies Agreements of the US, are alternative trade policy tools to reduce international trade barriers; (ii) direct flights facilitate the integration of internal markets as in the case of European Union.     

Monetary policy and credit cards: Evidence from a small open economy

This paper uses a unique monthly data set that covers the overall credit card usage in a small-open economy, Turkey, to investigate a possible credit channel of monetary policy transmission through credit cards. A reduced-form vector autoregression analysis is employed, where the forecast error variance decompositions are calculated for three-year windows over the period 2002–2009. It is shown that, during the recent financial crisis that has started in 2007, the monetary policy of Turkey has shifted toward focusing on output volatility and interest rate smoothing through setting short-term interest rates, while the inflation rate has been mostly affected by exchange rate movements and inflation inertia. Credit card usage has an increasing effect on inflation rates through time, requiring more policy emphasis on the credit channel through credit cards. When the effects of the credit view and the money view are compared, the former seems to be more effective on the real side of the economy, independent of the level of inflation.     

The inflation and inflation uncertainty relationship for Turkey: a dynamic framework

This article assesses the interaction between inflation and inflation uncertainty in a dynamic framework for Turkey by using monthly data for the time period 1984–2009. The bulk of previous studies investigating the link between inflation and inflation uncertainty employ Autoregressive Conditional Heteroskedasticity (ARCH)-type models, which consider inflation uncertainty as a predetermined function of innovations to inflation specification. The stochastic volatility in mean (SVM) models that we use allow for gathering innovations to inflation uncertainty and assess the effect of inflation volatility shocks on inflation over time. When we assess the interaction between inflation and its volatility, the empirical findings indicate that response of inflation to inflation volatility is positive and statistically significant. However, the response of inflation volatility to inflation is negative but not statistically significant.     

Contract length heterogeneity and the persistence of monetary shocks in a dynamic generalized Taylor economy

We develop the generalized Taylor economy (GTE) in which there are many sectors with overlapping contracts of different lengths. In economies with the same average contract length, monetary shocks will be more persistent when longer contracts are present. Using the Bils–Klenow distribution of contract lengths, we find that the corresponding GTE tracks the U.S. data well. When we choose a GTE with the same distribution of completed contract lengths as the Calvo, the economies behave in a similar manner.     

Turbulence in growing and declining industries

Turbulence over the industry life cycle is examined for the case of Portugal using the lowest possible level of industry aggregation, thus allowing for the use of panel data to study the evolution of product markets. Replacement of exiting firms by subsequent entrants plays a primary role in generating turbulence in high growth markets, while displacement of incumbents by recent entrants is the main selection force in declining markets. As the industry life cycle progresses, trial-and-error entry and entry mistakes decrease, and turbulence subsides.     

Mismeasurement of Distance Effects: The Role of Internal Location of Production

The estimated effects of distance in empirical international trade regressions are unrealistically high. Using state‐and‐sector level US exports data, this paper shows analytically and proves empirically that ignoring the internal location of production (of international exports), which leads to the overestimation of distance effects by about twofold, is a possible explanation. This overestimation is mostly attributed to the mismeasurement of the distance elasticity of trade costs when internal locations of production are ignored. A corrective distance index is proposed to avoid such mismeasurements and is shown to work well for the median sector. The results are robust to the consideration of alternative estimation methodologies and data sets.