1,721,041 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Accounting for technical efficiency differentials among smallholder tobacco farmers in Hurungwe Zimbabwe : impact of self-selection bias on contract participation
No full textDissertation (MSc (Agric))--University of Pretoria, 2018.This study used farm-level data to test whether contract farming can account for technical efficiency differentials amongst smallholder tobacco farmers from Hurungwe District in Zimbabwe independent of self-selection bias, in response to the need (i) to inform policy on contract farming in Zimbabwe as an agricultural finance model, and (ii) the literature on impact evaluation which hypothesizes that contract participation is not a random process. A sample of 240 smallholder tobacco farmers was split into a treatment (contract farmers) and a control group (non-contract farmers) to enable comparison. Using 2016/17 farm-level production data collected through face-to-face interviews by means of structured questionnaires, the study compared 75 contract and 165 non-contract farmers purposefully selected through stratified random sampling. A Cobb-Douglas Stochastic Frontier Production Function (SPF) model was used to estimate technical efficiency differentials across the sub-samples before and after accounting for self-selection bias using Propensity Score Matching (PSM) techniques.
Without accounting for self-selection bias, the results show that contract farmers had a mean technical efficiency score of 83 percent (95 percent CI 0.799: 0.851) compared to 81 percent (95 percent CI 0.794: 0.819) for non-contract farmers. A t-test for equality of means showed no significant differences between the two groups (t=-1.4332, p=0.153), suggesting that participation in contract farming cannot account for the observed technical efficiency differentials. However, using PSM techniques to account for self-selection bias and the stratified matching algorithm, the results show that contract farmers were on average 4.8 percent (t=4.075, p=0.012) more technically efficient relative to their non-contract counterparts, suggesting that accounting for self-selection bias matters in evaluating the impact. In the second stage of the SPF, bio-physical, socio-economic and policy variables were used as covariates to investigate determinants of technical efficiency across the two groups. For this group of farmers, the results suggest that household size (t=2.34, p=0.020) education level (t=1.96, p=0.061), access to extension services (t=2.22, p=0.027) and tobacco farming experience (t=3.48, p=0.001), and membership to a farmers’ group (t=2.84, p=0.008) showed a positive effect on technical efficiency. Meanwhile area allocated to tobacco farming (t=-2.57, p=0.011) and off-farm income (t=-2.49, p=0.013) showed a negative effect on technical efficiency. These results suggest that, in addition to formulating policies that promote contract farming, policy makers should also work on policies that improve access to extension services, education, promote the formation of farmers’ groups and encourage farmers to join them if productivity in smallholder tobacco farming sector is to be increased.
In a final model, the study established that membership to farmers’ groups (t=1.92, p=0.054), agricultural field day attendance (t=2.86, p=0.004), and farm size (t=4.65, p=0.000) increased the probability that farmers will choose to participate in contract farming. Thus, to promote contract farming, the government and policy makers play an important role by encouraging farmers to join farmers’ groups, attend agricultural field days in addition to making farmland accessible.
In conclusion, there exist considerable productivity losses due to inefficiency among this group of smallholder tobacco farmers that could be addressed at policy level. The study recommends contract farming as one policy vehicle that could be used to address such inefficiencies in capital-constrained smallholder agriculture. Further the existence of self-selection bias in contract participation must be addressed before assessing the impact of contract farming on technical efficiency of smallholder tobacco farmers. While acknowledging the role of contract farming in addressing productivity losses in the smallholder tobacco farming sector, the study also noted that there are additional variables that could be targeted by policy if these efficiency losses are to be addressed.Agricultural Economics, Extension and Rural DevelopmentMSc (Agric)Unrestricte
The impact of conservation agriculture adoption on farmer welfare : a comparative assessment of Kenya and Tanzania
Get PDFMini Dissertation (MSc (Agricultural Economics))--University of Pretoria, 2021.This paper used propensity score matching (PSM) technique and pooled cross-sectional data from 407 observations with 256 conservation agriculture (CA) adopters and 151 non-adopters from Kenya and Tanzania, to test whether CA causally improves smallholder farmer’s welfare. We find mixed results showing that CA has a statistically significant and positive impact on climate change adaptation, drought resilience, total maize production, food security, number of meals per day, household income, accumulation of productive assets, reduction of gender inequalities, improving social cohesion, reduced forest area cleared and soil health improvement. CA has a negative and statistically significant impact on total agricultural yield, agricultural production costs, and number of food insecure months, CA has no impact on addressing agricultural calendar bottlenecks. Since the cross-country analysis showed higher CA adoption rates in Tanzania relative to Kenya, policy could increase adoption rates in the latter by focussing on the less educated farmers, increasing access to input markets, demonstrating benefits from CA projects, and improving farmer mastery of CA technologies. The findings shed light on the role of sustainable agricultural practices and highlight cross-country experiences of CA technologies in improving the welfare of smallholder farmers.Agricultural Economics, Extension and Rural DevelopmentMSc (Agricultural Economics)Unrestricte
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Assessing technical, allocative and economic efficiency of smallholder maize producers using the stochastic frontier approach in Chongwe District, Zambia
Get PDFDissertation (MSc)--University of Pretoria, 2012.Smallholder farmers' efficiency has been measured by different scholars using different approaches. Both parametric and non-parametric approaches have been applied; each presenting unique results in some ways. The parametric approach uses econometric approaches to make assumptions about the error terms in the data generation process and also impose functional forms on the production functions. The nonparametric approaches neither impose any functional form nor make assumptions about the error terms. The bottom line of both approaches is to determine efficiency in production. In this study a parametric stochastic frontier approach is used to assess technical, allocative and economic efficiency from a sample of smallholder maize producers of Chongwe District, Zambia. This approach was chosen based on the fact that production among this group of farmers varies a great deal, and so the stochastic frontier attributes part of the variations to the random errors (which reflects measurement errors and statistical noise) and farm specific efficiency. Using a Cobb-Douglas frontier production function which exhibits self dual characteristics, technical efficiency scores for the sample of the smallholder maize producers are derived. With the parameter estimates(âi) obtained from the Cobb-Douglas stochastic production frontier, input prices (âi) and taking advantage of the self dual characteristics of the Cobb-Douglas, a cost function is derived. This forms the basis for calculating the farmers' allocative and economic efficiency. Results obtained from the study showed considerable technical, allocative and economic inefficiencies among smallholder maize producers. Technical Efficiency (TE) estimates range from 40.6 percent to 96.53 percent with a mean efficiency of 78.19 percent, while Allocative Efficiency (AE) estimates range from 33.57 to 92.14 percent with a mean of 61.81. The mean Economic Efficiency (EE) is 47.88 percent, with a minimum being 30 percent and a maximum of 79.26 percent. The results therefore indicate that inefficiency in maize production in Chongwe District is dominated by allocative and economic inefficiency. Additionally, in the two stage regression households characteristics: age; sex; education level; occupation; years in farming; land ownership; household size; access to extension and access to credit services; are regressed against technical efficiency scores using a logit function. Results obtained shows that land ownership, access to credit services, access to extension services, land ownership and education level of up to post primary (secondary and tertiary) have a positive influence on the households' technical efficiency. On the other hand, age of the household head; female headed household and lack of education (though not statistically significant at any confidence level) have a negative influence on this group of maize producers. In a similar two stage regression, access to extension services, membership to producer organisation, access to credit and disaster experienced on the farm such as floods, drought and hail, are regressed against AE. The result shows that access to extension services, access to credit services, membership to cooperatives and natural calamities affect AE. Results therefore show that there is a great deal of both allocative and economic inefficiency among smallholder maize farmers than there is technical inefficiency. To address these inefficiencies observed there is need to design policies that will ensure that environmental (e.g. poor land practices which lead to nutrient depletion from the soils), economic (e.g. high transport cost due to poor road infrastructure) and institutional issues (access to credit) are addressed. In other words, Government should help create credit facilities to provide affordable loans to this group of farmers. Additionally, there is need to improve extension systems to help educate farmers about better farming practices and other innovative technologies to further improve their efficiency in production. Issues of land ownership among this group of farmers needs to be addressed as this will not only raise confidence but will also ensure that their cost of production is reduced since there will be no need for payment of rental charges, and that farmers will adhere to good farming practices knowing they own title to land. CopyrightAgricultural Economics, Extension and Rural Developmentunrestricte
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Analysis of water supply unreliability and saving behaviour in Harare Zimbabwe: quantitative comparison of high- and low-density residential areas
Get PDFDissertation (MSc (Agric))--University of Pretoria, 2019.This study employs data from Harare, Zimbabwe, to assess the extent that unreliable domestic water supply challenges differentially affects households in high-density residential areas. Data are relative to those in low-density areas, based on the following household level measures: Water supply status, water related habits, water conservation consciousness, coping with water supply unreliability and managing future water supply unreliability. Harare was purposely selected because of its documented water supply unreliability challenges, causing suffering households. The study sampled 67 randomly selected households from high-density residential areas and 80 households from low-density residential areas, comprising 147 households. Structured questionnaires and face-to-face interviews were employed. Results concerning water supply status, indicate that when households access water from primary municipal sources, unreliable supply challenges do not indicate differential impacts. When constrained to obtain households from secondary sources, those in high-density areas are inclined to use community boreholes (χ2 = 93.25, p = 0.000) or to purchase water from bulk sellers (χ2 = 20.60, p = 0.000). Households in low-density areas are inclined to obtain water from private boreholes (χ2 = 13.99, p = 0.000) or private wells (χ2 = 12.67, p = 0.000). Households from high-density areas are also inclined to endure inadequate water supply pressure (χ2 = 15.6249, p = 0.000), unpredictable water supply intermittency (χ2 =4.1687, p = 0.041) and water quality they perceive (χ2 = 3.2165, p = 0.073) and observe (χ2 = 6.2953, p = 0.012) appears inadequate. The results regarding water related habits, indicate that unreliable supply challenges have differential impacts on low-density households compared with high-density households. Households in low-density areas are inclined to install showers for personal hygiene (χ2 =46.1558, p = 0.000). Households in high-density areas are inclined to waive water intensive practices, such as frequent floor mopping (χ2 =21.3260, p = 0.000) and rinsing of dishes (χ2 =4.2397, p = 0.039), at the cost of their personal and household hygiene. The results concerning water conservation consciousness, indicate that unreliable supply challenges have certain differential impacts on low-density households and high-density households. Households in low-density areas are inclined to install water conservation devices (χ2 =21.0262, p = 0.000), water flow regulation devices (χ2 =27.3979, p = 0.000) and accept legislation to encourage water conservation by limiting the quantity of water use supplied by the municipality (χ2 =9.6560, p = 0.002). The results concerning coping with water supply unreliability, indicate that unreliable supply challenges have certain differential impacts on low-density households and high-density households. Households in low-density areas are inclined to use enhancement strategies to cope with inadequate water pressure (χ2 = 106.0411, p = 0.000), inadequate water intermittency (χ2 =25.3845, p = 0.000) and inadequate water quality (χ2 = 72.1068, p = 0.000) from their primary water supply sources. Households in high-density areas are inclined to use accommodation strategies to cope with inadequate water pressure (χ2 = 106.0411, p = 0.000), inadequate water intermittency (χ2 =25.3845, p = 0.000) and inadequate water quality (χ2 = 72.1068, p = 0.000) from their primary water supply sources. Finally, concerning managing future water supply unreliability, households in low-density areas are inclined to accept an exemption from water interruption at the cost of paying higher water bills (χ2 = 18.5001, p = 0.000). The study concludes that unreliable water supply results in suffering, disproportionately high on households in high-density areas as they bear the significant share of the cost. The study recommends that the Harare Municipality should consider improving the reliability of the water supply to the Harare residents. During water interruption periods, they should consider residents located in high-density areas in addition, as they suffer the most from residents located in low-density areas. The policy-makers should also consider developing policies to address the welfare loss caused by the unreliable water supply challenge in the city of Harare.Agricultural Economics, Extension and Rural DevelopmentMSc (Agric)Unrestricte
Accounting for self-selection bias in assessing impacts of agricultural innovations : the case of farmer support programs in the Eastern Cape
Get PDFMini Dissertation (MSc Agric (Agricultural Economics))--University of Pretoria, 2021.The study uses cross-sectional data to test whether FSPs improve technical efficiencies (TEs) of smallholder maize farmers. Using plot level data collected from 30 FSP and 66 non-FSP farmers drawn from Mgojweni, Mabetshe, Lujecweni, Bantingville, Canzibe and Dumasi villages of the Eastern Cape, this study estimates a Cobb-Douglas stochastic production frontier and uses it to compare the efficiency scores of the two farmer types. The results show that FSP adopters had relatively higher TE scores, with over 50% having scores of above 70%. However, a t-test for equality of mean TE scores revealed no statistically significant differences between them (t=-1.3969, p=0.1662), suggesting that the FSPs cannot explain the TE variances. Given that participation in FSPs was not random, a propensity score matching techniques was used to account for self-selection bias. After accounting for self-selection bias the results revealed that FSP adopters were on average 205% more efficient relative to non-adopters. These results underscore the importance of accounting for self-selection bias in demonstrating the impact of agricultural innovations.Agricultural Economics, Extension and Rural DevelopmentMSc Agric (Agricultural Economics)Unrestricte
The impact of conservation agriculture adoption on farmer welfare: a comparative assessment of Zambia and Zimbabwe
Get PDFDissertation (MSc Agric (Agricultural Economics))--University of Pretoria, 2021.A comprehensive study on the impact of conservation agriculture on farmer welfare has largely remained empirically untested in Africa. Where the impact of conservation agriculture has been estimated, essential non-monetary services such as food security, soil health, social cohesion, gender disparities, resilience to drought, adaptation to climate change and environmental sustainability have not been studied together. In addition, no study compares the adoption and impact of CA between Zimbabwe and Zambia. This study uses pooled cross-sectional data from 279 project and 127 non-project participants drawn from Zambia and Zimbabwe to test whether conservation agriculture (CA) causally improves smallholder farmer welfare. We estimated the propensity score matching model using the nearest neighbour, stratification and kernel matching algorithms to determine the causal impact of conservation agriculture on farmer welfare. The results show that CA has statistically significant causal impact on increasing total agricultural yield (t=6.332, p=0.000), maize yield (t=4.806, p=0.000), resilience to drought (t=7.102, p=0.000), adaptation to climate change impacts (t=6.496, p=0.000), number of meals per day (t=5.103, p=0.000), food security (t=3.639, p=0.000), household income (t=1.694, p=0.10), accumulation of productive assets (t=2.338, p=0.05), ability to address agricultural calendar bottlenecks (t=6.123, p=0.000), increasing production costs (t=2.639, p=0.01), addressing gender disparities (t=5.743, p=0.000), improving soil health (t=6.581, p=0.000) and reducing the amount of forest area cleared per year (t=2.951, p=0.01). However, CA had no statistically significant impact on the number of food-insecure months and social cohesion. We observe that Zimbabwe farmers have access to 2.7 meals per day compared to Zambia’s 2.9 meals per day. It shows that conservation agriculture has had more impact in Zambia than in Zimbabwe. Since the cross-country analysis shows that farmers in Zimbabwe are more likely to adopt CA, policy in Zambia could similarly increase adoption rates by focussing on promoting the technology among older farmers, especially those who perceive soil fertility as low. This study shows that CA improves the welfare of smallholder farmers through improved agronomic, food security, economic, social and environmental benefits that it offers. Therefore, the results point to the need to promote extension services to build capacity among farmers, improve markets for inputs such as jab planters and Chaka hoes (CA specialised weeding hoes), and introduce and train farmers on the use of herbicides to reduce labour demands. Agriculture extension remains the most reliable source of information on better production methods and agricultural practices, including labour saving and production intensification.
Keywords: Conservation agriculture, propensity score matching, welfare outcomes, Zambia, Zimbabwe.Agricultural Economics, Extension and Rural DevelopmentMSc Agric (Agricultural Economics)Unrestricte
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