The effect of barge and ocean freight price volatility in international grain markets

Short‐run responses of export and domestic shares of total agricultural output to changes in stocks of domestic savings (SAV), development assistance (ODA), private foreign commercial capital (PFX) and other variables is investigated. A profit function approach is used. Time series data for 19 sub‐Saharan African countries are pooled into three panels using similarities in changes in economic policy regime. Statistical evidence suggests that for the panel of countries that were undertaking liberalized economic reforms, the slope coefficients of some of the variables in the models have changed significantly between 1970–1980 and 1981–1993. For the 1981–1993 period, the impacts of ODA, PFX and SAV on export and domestic shares were different for this panel. The effect of increases in agricultural labor was different across the three panels. There is also evidence that productivity growth in the export agriculture sub‐sector is negative in all the groups. It is recommended that to halt the decline in export share of agricultural output in the group of countries that have undertaken substantial improvements in economic policy environment, efforts must be made to reduce the negative impact of domestic savings and agricultural labor, while at the same time working to reduce the bias of development assistance against food security.     

Derivative pricing model and time‐series approaches to hedging: A comparison

This research compares derivative pricing model and statistical time‐series approaches to hedging. The finance literature stresses the former approach, while the applied economics literature has focused on the latter. We compare the out‐of‐sample hedging effectiveness of the two approaches when hedging commodity price risk using futures contracts. For various methods of parameter estimation and inference, we find that the derivative pricing models cannot out‐perform a vector error‐correction model with a GARCH error structure. The derivative pricing models' unpalatable assumption of deterministically evolving futures volatility seems to impede their hedging effectiveness, even when potentially foresighted optionimplied volatility term structures are employed. © 2005 Wiley Periodicals, Inc. Jrl Fut Mark 25:613–641, 2005     

Social investment: Subjectivism, sublation and the moral elevation of success

Investment products that deploy ethical values and social considerations in portfolio construction have persisted since the 1980s. Pitting Habermasian discourse ethics against Foucauldian power relations and radical institutionalism, the paper argues that socially directed mutual funds ascribe capital markets with validities of high moral magnitude, work up extant tendencies toward financial hegemony and stymie criticism of the political–economic order. Institutional pressures do not permit the exercise of an ethic stronger than an aesthetic care of the self. The balance struck between economic and social priorities is investigated by interviewing investment managers, reviewing archival material and surveying the attitudes of unit holders in retail social mutual funds.     

Crack spread hedging: accounting for time‐varying volatility spillovers in the energy futures markets

Crude oil, heating oil, and unleaded gasoline futures contracts are simultaneously analysed for their effectiveness in reducing price volatility for an energy trader. A conceptual model is developed for a trader hedging the ‘crack spread’. Various hedge ratio estimation techniques are compared to a Multivariate GARCH model that directly incorporates the time to maturity effect often found in futures markets. Modelling of the time‐variation in hedge ratios via the Multivariate GARCH methodology, and thus taking into account volatility spillovers between markets is shown to result in significant reductions in uncertainty even while accounting for trading costs. Copyright © 2002 John Wiley & Sons, Ltd.     

Disproving Causal Relationships Using Observational Data*

Economic theory is replete with causal hypotheses that are scarcely tested because economists are generally constrained to work with observational data. We describe a method for testing a hypothesis that one observed random variable causes another. Contingent on a sufficiently strong correspondence between the two variables, an appropriately related third variable can be employed for the test. The logic of the procedure naturally suggests strong and weak grounds for rejecting the causal hypothesis. Monte Carlo results suggest that weakly grounded rejections are unreliable for small samples, but reasonably reliable for large samples. Strongly grounded rejections are highly reliable, even for small samples.     

Causality in futures markets

This study tests causal hypotheses emanating from theories of futures markets by utilizing methods appropriate for disproving causal relationships with observational data. The hedging pressure theory of futures markets risk premiums, the generalized version of the normal backwardation theory of Keynes, is rejected. Theories predicting that the activity levels of speculators or uninformed traders affect levels of price volatility, either positively or negatively, are also rejected. © 2006 Wiley Periodicals, Inc. Jrl Fut Mark 26:1039–1057, 2006