The economic potential of precision nitrogen application with wheat based on plant sensing

Plant-based precision nitrogen fertilizer application technologies have been developed as a way to predict and precisely meet nitrogen needs. Equipment necessary for precision application of nitrogen, based on sensing of growing wheat plants in late winter, is available commercially, but adoption has been slow. This article determines the expected profit from using a plant-sensing system to determine winter wheat nitrogen requirements. We find that plant-sensing systems have the potential to be more profitable than traditional nonprecise systems, but the existing system simulated was roughly breakeven with a traditional system.     

On Choosing and Bounding Probability Metrics

When studying convergence of measures, an important issue is the choice of probability metric. We provide a summary and some new results concerning bounds among some important probability metrics/distances that are used by statisticians and probabilists. Knowledge of other metrics can provide a means of deriving bounds for another one in an applied problem. Considering other metrics can also provide alternate insights. We also give examples that show that rates of convergence can strongly depend on the metric chosen. Careful consideration is necessary when choosing a metric.     

Food price increases and net food importing countries: lessons from the recent past

Recent increases in food and other commodity prices have highlighted concerns that many poor countries are net food importers and higher food prices would worsen their trade balances. In this article, we analyze the changes in food trade balances associated with the 32% increase in food prices from 2000/2001 to 2004/2005. We find a small deterioration in food trade balances of low‐income countries and an improvement in middle‐income countries. The deterioration is most severe for countries in conflict and small island states, so attention should be placed first on these countries and on a few very‐low‐income countries that are also vulnerable. Because low‐income countries as a group had much lower agricultural GDP growth rates than middle‐income countries, the answers to food vulnerability in low‐income countries should probably be addressed within the context of incentives for agricultural production.     

Formation of diacrylic acid during acrylic acid storage

Diacrylic acid (β-acryloxypropionic acid) forms spontaneously in bulk acrylic acid by a Michael-addition reaction. Fresh samples of acrylic acid containing 0.08–2.9% (m/m) levels of water were stored at constant temperatures of 15, 25, 35, and 45°C up to 65 days. An empirical equation to predict diacrylic acid formation was generated from the data.     

Estimating the impact of farmer field schools in sub‐Saharan Africa: the case of cocoa

This study measures the economic impact of the first phase of the Cocoa Livelihood Program (CLP‐I), a current World Cocoa Foundation (WCF) project, sponsored by the Bill and Melinda Gates Foundation and aimed at improving the livelihood of over 200,000 small cocoa producers in sub‐Saharan Africa via training, crop diversification, and farmer‐based organizations. Using data collected from 2,048 pre‐ and post‐CLP‐I interviews of cocoa producers in Ghana, Cote d'Ivoire, Nigeria, and Cameroon, the results show that yield enhancements attributable to CLP‐I are 32%, 34%, 50%, and 62% in Ghana, Côte d'Ivoire, Nigeria, and Cameroon, respectively. Using a total program cost of $151–$200 per beneficiary and estimated annual benefits of $109–$322 per beneficiary over 25 years, the benefit‐cost ratios are estimated to range from $18 to $62 for every dollar spent on human capital development. These results suggest the WCF should endeavor to increase the number of farmers who receive all, not some, of the components of the program. This would not only help ensure that each producer obtains as much human capital as possible from each of the training programs but increases the probability of reaching the CLP goal of doubling the income of cocoa‐growing households.     

A parametric control function approach to estimating the returns to schooling in the absence of exclusion restrictions: an application to the NLSY

An innovation which bypasses the need for instruments when estimating endogenous treatment effects is identification via conditional second moments. The most general of these approaches is Klein and Vella (J Econom 154:154–164, 2010), which models the conditional variances semiparametrically. While this is attractive, as identification is not reliant on parametric assumptions for variances, the nonparametric aspect of the estimation may discourage practitioners from its use. This paper outlines how the estimator can be implemented parametrically. The use of parametric assumptions is accompanied by a large reduction in computational and programming demands. We illustrate the approach by estimating the return to education using a sample drawn from the National Longitudinal Survey of Youth 1979. Accounting for endogeneity increases the estimate of the return to education from 6.8 to 11.2%.     

The Volatility and Transmission of Equity Returns among the G-7 Countries: the post-Bretton Woods experience

This paper models the volatility of national stock market returns of the G-7 countries using ARCH and GARCH modeling techniques. Then, via the use of vector autoregression analysis, the international transmission of volatility among the countries is explored for the period between April 1973 and July 1990. Variance decompositions are calculated in order to quantify the impacts of volatility shocks in one market on the others. Impulse response functions are used to inspect the dynamic responses of domestic and foreign volatility shocks. Results indicate that volatility transmission among the G-7 countries is the norm in the post-Bretton Woods era. Further, we find that volatility shocks are generally absorbed within six to nine months.     

The diary of a charity donor: an exploration of research information from the Royal Mail Consumer Panel and Mail Characteristics Survey

This paper looks at direct mail in the United Kingdom across all market sectors and in detail at the charity sector. It uses the research information that Royal Mail has been collecting foroveradecadetoshowthegrowthofthe medium. The diary system used by the Consumer Panel gives an insight into the typical donor and their relationship with charities. This paper looks only at direct mail: ‘personally addressed advertising material that is delivered through the post’. This definition means that leaflets put through the letterbox are excluded. Copyright © 1999 Henry Stewart Publications