Export taxes versus buffer stocks as optimal export policies under uncertainty

Optimal state-dependent export taxes and costly-to-store buffer stocks are compared in their welfare implications for an exporter possessing monopoly power in the international trade of a volatile commodity. Optimal stochastic control is used to derive the optimal buffer stock rules. It is shown that, if the internal and external fluctuations facing the exporter are large, if the storage costs are low, and if the price elasticity of export supply is small relative to that of export demand, the exporter would gain more from a buffer stock than from a optimal export tax. World welfare is always increased by buffer stocks, as opposed to tariffs; and, under some conditions, the foreign country might also benefit and, hence, not retaliate.     

Productivity,credit, risk,and the demand for weather index insurance in smallholder agriculture in Ethiopia

The article explores the relationship between fertilizer use and the demand for weather index insurance (WII) among smallholder farmers in Ethiopia. We examine whether fertilizer use is profitable under current smallholder production conditions, whether risk‐related factors affect fertilizer use, and we estimate the returns to inputs in the agricultural production function in the absence of insurance. We then study how these primitives of agricultural production functions relate to insurance demand. The study compares a survey‐based estimate of willingness to pay with actual uptake for the weather insurance, finding the stated and actual demand to be almost completely uncorrelated. While those with high marginal returns to inputs say they would purchase insurance, only those with low marginal returns actually do, consistent with the stated purpose of the product as input insurance. Insurance demand proves to be highly responsive to the existence and amount of randomly allocated insurance vouchers.     

Volatility Forecasting and Time‐varying Variance Risk Premiums in Grains Commodity Markets

In this paper we examine empirically the predictive power of model‐free option‐implied variance and skewness in wheat, maize and soybeans derivative markets. We find that option‐implied risk‐neutral variance outperforms historical variance as a predictor of future realised variance for these three commodities. In addition, we find that risk‐neutral option‐implied skewness significantly improves variance forecasting when added in the information variable set. Variance risk premia add significant predictive power when included as an additional factor for predicting future commodity returns.     

Quantum models for decision making and opinion dynamics the role of the Lie algebras

Quantum decision models provide a theoretical framework to study decision making and opinion dynamics. The role of Lie algebras is fundamental in these models to get the opinion dynamics without violating the uncertainty principle. A particular case is developed to show the potentiality of our method.     

Assessing the Vulnerability to Price Spikes in Agricultural Commodity Markets

We examine empirically the predictability of conditions associated with a higher probability of a price spike in agricultural commodity markets. We find that the forward spread is the most significant indicator of probable price jumps in maize, wheat and soybeans futures markets, a result which is in line with the ‘Theory of Storage’. We additionally show that some option-implied variables add significant predictive power when added to the more standard information variable set. Overall, the estimated probabilities of large price increases from our probit models exhibit significant correlations with historical sudden market upheavals in agricultural markets.