A weighted max-min model for fuzzy multi-objective supplier selection in a supply chain

Supplier selection is one of the most important activities of purchasing departments. This importance is increased even more by new strategies in a supply chain. Supplier selection is a multi-criteria decision making problem in which criteria have different relative importance. In practice, for supplier selection problems, many input information are not known precisely. The fuzzy set theories can be employed due to the presence of vagueness and imprecision of information. A weighted max-min fuzzy model is developed to handle effectively the vagueness of input data and different weights of criteria in this problem. Due to this model, the achievement level of objective functions matches the relative importance of the objective functions. In this paper, an analytic hierarchy process (AHP) is used to determine the weights of criteria. The proposed model can help the decision maker (DM) to find out the appropriate order to each supplier, and allows the purchasing manager(s) to manage supply chain performance on cost, quality and service. The model is explained by an illustrative example.     

Inequality and growth in the United States: is there asymmetric response at the state level?

A previous study that tried to assess the impact of economic growth on income inequality in the U.S. used state-level data and an ARDL panel model to conclude that economic growth worsens income inequality in the U.S. In this article, we use the same data set but an ARDL time-series model applied to each state in the U.S. to show that the above conclusion is only valid in 20 states. Additionally, we use a nonlinear ARDL approach to show that the effects are asymmetric in the short run as well as in the long run. Significant long-run asymmetric effects reveal that in 28 states both an increase and a decrease in real output have worsened income distribution.     

The dilemma of cheap food and self-sufficiency: The case of wheat in Iran

Self-sufficiency in wheat has been one of the major goals of Iranian agricultural policies since the Revolution of 1979. Even so, the country failed to achieve this goal by the early 2000s, despite a satisfactory growth in wheat production. This paper addresses this failure and the political difficulties in introducing reforms that would reduce the need for import. First, the production and consumption of wheat are examined. The conclusion is that the cheap-bread policy has mainly been responsible for the imbalances between domestic supply and demand, and the continued reliance on wheat imports. Moreover, the paper argues that the subsidy program is an expensive safety net for the needy and shows that the Iranian government has intended to reform the program since the early 1990s. However, subsidy reforms are politically sensitive, especially in developing countries where subsidies are considered very important, both for supporting the poor and for political stability. An analysis of the Iranian attempts at subsidy reform suggests that they have not yet succeeded, mainly due to such political considerations.     

On the effects of income volatility on income distribution: Asymmetric evidence from state level data in the U.S.

A previous study that tried to assess the impact of income volatility on income inequality in the U.S. used state level data and a balanced panel model to conclude that increased volatility worsens income distribution in the U.S., which implies that decreased volatility should reduce inequality. We use the same data set that is extended by nine years and revisit the issue using linear and nonlinear ARDL time-series models to show that the above conclusion does not hold in every state. While we discover short-run asymmetric effects of income volatility on a measure of inequality in most states, they translate to long-run asymmetric effects only in 16 states. Both increased volatility and decreased volatility are found to have unequalizing effects on income distribution in these states.