We investigate conditions sufficient for identification of average treatment effects using instrumental variables. First we show that the existence of valid instruments is not sufficient to identify any meaningful average treatment effect. We then establish that the combination of an instrument and a condition on the relation between the instrument and the participation status is sufficient for identification of a local average treatment effect for those who can be induced to change their participation status by changing the value of the instrument. Finally we derive the probability limit of the standard IV estimator under these conditions. It is seen to be a weighted average of local average treatment effects.

Evolution and Rationality Some Recent Game-Theoretic Results. Identification and Estimation of Local Average Treatment Effects

Input subsidy programs in sub-Saharan Africa: a synthesis of recent evidence

African swine fever is a devastating disease that can result in death in almost all infected pigs. The continuing spread of African swine fever from Africa to Europe and recently to the high-pig production countries of China and others in Southeast Asia threatens global pork production and food security. The African swine fever virus is an unusual complex DNA virus and is not related to other viruses. This has presented challenges for vaccine development, and currently none is available. The virus is extremely well adapted to replicate in its hosts in the sylvatic cycle in East and South Africa. Its spread to other regions, with different wildlife hosts, climatic conditions, and pig production systems, has revealed unexpected epidemiological scenarios and different challenges for control. Here we review the epidemiology of African swine fever in these different scenarios and methods used for control. We also discuss progress toward vaccine development and research priorities to better understand this complex disease and improve control.

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African Swine Fever Epidemiology and Control

L'efficacite technique et d'echelle des exploitations agricoles polonaises est calculee par la methode Data envelopment analysis. L'etude porte sur les differences selon l'orientation productive, en grandes cultures ou elevage, a deux dates de la transition, en 1996 et en 2000. L'article examine de plus la variabilite statistique des resultats d'efficacite. Ceux-ci sont revus a la lumiere des intervalles de confiance construits grâce au bootstrapping. En moyenne, les exploitations d'elevage ont une efficacite technique et d'echelle superieure aux exploitations de grandes cultures. L'efficacite d'echelle est toutefois tres elevee pour les deux orientations. L'inefficacite technique semble donc due principalement a une inefficacite technique pure, c'est-a-dire a une gestion inefficace. La faible education des agriculteurs en est une raison majeure. En 2000, 64% des exploitations d'elevage et 86% des exploitations de grandes cultures presentaient des retours d'echelle croissants. Ce resultat suggere des recommandations politiques afin de supprimer les incitations a garder une structure operationnelle fragmentee et de stimuler le marche de la terre. Il s'agit en particulier d'ameliorer la legislation concernant la location des terres et de modifier le systeme de retraite agricole.

Technical and scale efficiency of crop and livestock farms in Poland : does specialization matte r?

https://halshs.archives-ouvertes.fr/halshs-01290714/document

Household fuel use in developing countries: Review of theory and evidence

This study assessed the determinants of intensity of adoption of Improved Rice Varieties (IRVs) and the effect of market participation on farmers’ welfare in Nigeria using the Tobit and Heckman two-stage models, respectively. The sample consists of cross-sectional data of 600 rice farmers selected randomly from three notable rice producing States in Nigeria. The variables that positively and significantly influenced the intensity of IRVs adoption include income from rice production, membership of a farmers’ organization, and the distance to the nearest sources of seed, cost of seed, yield and level of training. Gender of household head, access to improved seed, years of formal education, and average rice yield were those variables that are positive and statistically significant in increasing the probability that a farmer would participate in the market. The result further suggests that any increase in the farmers’ welfare is conditional on the probability of the farmer participating in the rice output markets. In addition, higher yield, income from rice production, gender of household head, and years of formal education are the variables that are positive and statistically significant in determining households’ welfare. Therefore, it is recommended that formation of associations among the rural farmers should be encouraged. Access to seed and information about the IRVs are also essential to increase the intensity of its adoption. Programmes to improve contact with extension agents, increased access to credit, raising educational background and increasing the area devoted to cultivating IRVs are the factors to be promoted in order to increase market participation and hence improve the welfare of rural households.

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Agricultural technology adoption, commercialization and smallholder rice farmers’ welfare in rural Nigeria

The impact of seed vouchers on poverty reduction among smallholder rice farmers in Nigeria

The present study aims to explore economic and socio-demographic factors that influence a household’s probability to switch from firewood to cleaner fuels (kerosene and LPG) in northern Cameroon. The paper employs an ordered probit model to construct cooking patterns and fuel choices. Three main cooking sources are considered: firewood, kerosene, and liquefied petroleum gas. Utilized data are derived from a national survey conducted in 2004 by the Cameroonian National Institute of Statistics. The study analyzes the data related to the Sudano-Sahelian agro-ecological zone, which is one of the most affected by land degradation and decertification. While results indicate that there is a potential for a transition from traditional to cleaner fuels in the studied region, this transition is still in its earlier stage. The research demonstrates that firewood and kerosene prices, age of household heads, educational level of household heads and willingness to have a gas cylinder, as well as type of dwelling have a statistically significant impact on fuel-switching decisions.

/pdf/modeling-fuel-choice-among-households-in-northern-cameroon-3mxd1ytycv.pdf

Modeling Fuel Choice among Households in Northern Cameroon

Since irrigation water is assumedly the predominant factor determining crop yield, the difference in irrigation water availability across the administrative sub-districts of the Khorezm region, Central Asia, also inflicts an unequal distribution of agricultural revenues. Considering the national aim of a fair distribution and efficient use of resources, here we analyze the relationships between irrigation water access and rural welfare from 2000 to 2007 by descriptive statistics. Analyses revealed not only the general dependency of agricultural revenue on irrigation water availability, but also occurrence of low land productivity during water scarce years and, irrespective of the annual water availability, in some tail end regions each year. Furthermore, apart from irrigation water availability, land productivity was also impacted by soil quality, cropping structure, and type of land ownership. Fair distribution of water and land resources should also take into consideration population density. It is argued that an anticipated equal and efficient water allocation necessitates improved irrigation water conveyance, distribution, and application efficiency via best water management practices. Liberalization of markets, development of a market infrastructure and improvement in yields also contribute to increased land and water productivity.

https://www.mdpi.com/2073-4441/2/3/668/pdf?y=1

Aziz A. Karimov

Papers

Agricultural technology adoption, commercialization and smallholder rice farmers’ welfare in rural Nigeria

The impact of seed vouchers on poverty reduction among smallholder rice farmers in Nigeria

Modeling Fuel Choice among Households in Northern Cameroon

Impact of Water Availability on Land and Water Productivity: A Temporal and Spatial Analysis of the Case Study Region Khorezm, Uzbekistan

Importance of socio-economic factors in the collection of NTFPs: The case of gum arabic in Kenya