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We measure bias and efficiency of parameter estimates in the conditional logit (CL) and independent availability logit (IAL) models. Our Monte Carlo experiments consider both no choice set formation where individuals choose from the full set of alternatives, and when choice sets are stochastically formed and individuals choose from a subset of all alternatives. We also compare the performance of the two models using empirical data on paddlefish angler preferences and catch-and-release regulations in Oklahoma. Both the CL and IAL work well when their own assumptions hold, but not under the alternative’s assumptions. The IAL approximates the attribute-based cutoff well in empirical data. While neither the IAL nor the CL is universally preferred, based on our findings, we recommend the IAL when the true consideration sets are unknown.
John N. Ng’Ombe; B. Wade Brorsen. The Effect of Including Irrelevant Alternatives in Discrete Choice Models of Recreation Demand. Computational Economics 2021, 1 -27.
AMA StyleJohn N. Ng’Ombe, B. Wade Brorsen. The Effect of Including Irrelevant Alternatives in Discrete Choice Models of Recreation Demand. Computational Economics. 2021; ():1-27.
Chicago/Turabian StyleJohn N. Ng’Ombe; B. Wade Brorsen. 2021. "The Effect of Including Irrelevant Alternatives in Discrete Choice Models of Recreation Demand." Computational Economics , no. : 1-27.
Crop diversification has been shown to help mitigate climate change effects for farmers. While previous research shows that crop diversification may increase or decrease technical efficiency in different regions, research on whether crop diversification involves a tradeoff between technical efficiency and income variability is limited. Using agricultural production data from Northern Ghana, this study uses the stochastic input distance function to examine the effects of crop diversification on technical efficiency. The study further explores effects of crop diversification on income variability using an ordinary least square regression to understand the nexus between technical efficiency and income variability in crop diversification. The results show evidence against a ‘tradeoff’ between technical efficiency and income stability for farmers in Northern Ghana. We find that crop diversification significantly improves efficiency and reduces income variability in Northern Ghana, so farmers do not have to give up efficiency for income stability or vice versa. This suggests that crop diversification could be an ideal Climate Smart Agricultural (CSA) strategy for promoting agricultural growth and resilience in Northern Ghana. While our data has a maximum of three crops, which could limit generalization of results to farmers who grow more than three crops, our results make a novel contribution to the literature on crop diversification.
Agness Mzyece; John N. Ng'Ombe. Crop diversification improves technical efficiency and reduces income variability in Northern Ghana. Journal of Agriculture and Food Research 2021, 5, 100162 .
AMA StyleAgness Mzyece, John N. Ng'Ombe. Crop diversification improves technical efficiency and reduces income variability in Northern Ghana. Journal of Agriculture and Food Research. 2021; 5 ():100162.
Chicago/Turabian StyleAgness Mzyece; John N. Ng'Ombe. 2021. "Crop diversification improves technical efficiency and reduces income variability in Northern Ghana." Journal of Agriculture and Food Research 5, no. : 100162.
This paper examines the effects of regional characteristics on the spread of the highly pathogenic avian influenza (HPAI) during Korea’s 2016–2017 outbreak. A spatial econometric model is used to determine the effects of regional characteristics on HPAI dispersion using data from 162 counties in Korea. Results indicate the existence of spatial dependence, suggesting that the occurrence of HPAI in a county is significantly influenced by neighboring counties. We found that larger size poultry, including laying hens, breeders, and ducks are significantly associated with a greater incidence of HPAI. Among poultry, we found ducks as the greatest source of the spread of HPAI. Our findings suggest that those regions that are spatially dependent with respect to the spread of HPAI, such as counties that intensively breed ducks, should be the focus of surveillance to prevent future epidemics of HPAI.
Meilan An; Jeffrey Vitale; Kwideok Han; John Ng’Ombe; Inbae Ji. Effects of Spatial Characteristics on the Spread of the Highly Pathogenic Avian Influenza (HPAI) in Korea. International Journal of Environmental Research and Public Health 2021, 18, 4081 .
AMA StyleMeilan An, Jeffrey Vitale, Kwideok Han, John Ng’Ombe, Inbae Ji. Effects of Spatial Characteristics on the Spread of the Highly Pathogenic Avian Influenza (HPAI) in Korea. International Journal of Environmental Research and Public Health. 2021; 18 (8):4081.
Chicago/Turabian StyleMeilan An; Jeffrey Vitale; Kwideok Han; John Ng’Ombe; Inbae Ji. 2021. "Effects of Spatial Characteristics on the Spread of the Highly Pathogenic Avian Influenza (HPAI) in Korea." International Journal of Environmental Research and Public Health 18, no. 8: 4081.
This study determines the impact of the adoption of improved rice varieties on household food security using farm‐level data from 900 households in Northern Ghana. We employed the doubly robust inverse probability weighted regression adjustment procedure complementary with a propensity score matching approach on two indicators of food security (household dietary diversity score and subjective food security). Across all the various estimation procedures, we observed consistent positive effects of the adoption of improved rice varieties on household food security. Policies that enhance diffusion and adoption of improved rice varieties should be encouraged to improve food security among farm households.
Wencong Lu; Kwabena Nyarko Addai; John N. Ng'Ombe. Impact of improved rice varieties on household food security in Northern Ghana: A doubly robust analysis. Journal of International Development 2021, 33, 342 -359.
AMA StyleWencong Lu, Kwabena Nyarko Addai, John N. Ng'Ombe. Impact of improved rice varieties on household food security in Northern Ghana: A doubly robust analysis. Journal of International Development. 2021; 33 (2):342-359.
Chicago/Turabian StyleWencong Lu; Kwabena Nyarko Addai; John N. Ng'Ombe. 2021. "Impact of improved rice varieties on household food security in Northern Ghana: A doubly robust analysis." Journal of International Development 33, no. 2: 342-359.
While contract farming and interlocked contractual arrangements (ICAs) are generally perceived to resolve persistent market failures and improve smallholder farmers' welfare in developing countries, uncertainties remain as to whether these arrangements enhance welfare because of farmers' low marketed volumes and margins. To account for potential selection bias, non-Gaussian and missing data problems, a robust two-stage Bayesian instrumental variable approach is used to determine the impact of dairy farmers' participation in ICAs on household income and milk revenue. Data are from smallholder dairy farmers in Zambia. We find that male household heads, wealth, experience selling to milk collection centres (MCCs), livestock holding, milking parlour ownership, landholding, and access to marketing information positively affect farmers' probability to participate in ICAs. However, increased off-farm income and distance to MCCs limit their participation. While some socioeconomic variables have significant positive effects of affecting ICA participation on household welfare, we find no sufficient evidence of causal effects of ICAs on household incomes and milk revenue among dairy farmers. Thus, while ICAs enhance smallholder farmers' access to markets, they may not address high rural poverty rates in developing countries. We provide some insights by which performance of ICAs in the dairy sector may be improved.
Rebecca N. Kiwanuka-Lubinda; John N. Ng’Ombe; Charles Machethe. Impacts of interlocked contractual arrangements on dairy farmers’ welfare in Zambia: a robust Bayesian instrumental variable analysis. Agrekon 2021, 1 -21.
AMA StyleRebecca N. Kiwanuka-Lubinda, John N. Ng’Ombe, Charles Machethe. Impacts of interlocked contractual arrangements on dairy farmers’ welfare in Zambia: a robust Bayesian instrumental variable analysis. Agrekon. 2021; ():1-21.
Chicago/Turabian StyleRebecca N. Kiwanuka-Lubinda; John N. Ng’Ombe; Charles Machethe. 2021. "Impacts of interlocked contractual arrangements on dairy farmers’ welfare in Zambia: a robust Bayesian instrumental variable analysis." Agrekon , no. : 1-21.
This study analyzes the self-reported intake of dietary supplements (DS) and their effects on perceived health well-being from a survey with 1210 adult respondents in Korea. To account for selectivity bias from observable confounders, we use a propensity score matching (PSM) model. Our findings show that demographics, health concerns, family history of disease, frequency of hospital visits, and regular exercise are positively associated with intake of DS among consumers. Results from PSM show that the intake of DS leads to significant improvements in perceived health well-being among DS takers relative to DS non-takers regardless of gender, urban residence, having self-reported diseases or not. The paper concludes with implications for policies that promote intake of DS in Korea.
Donghoon Kim; Inbae Ji; John Ng’Ombe; Kwideok Han; Jeffrey Vitale. Do Dietary Supplements Improve Perceived Health Well-Being? Evidence from Korea. International Journal of Environmental Research and Public Health 2021, 18, 1306 .
AMA StyleDonghoon Kim, Inbae Ji, John Ng’Ombe, Kwideok Han, Jeffrey Vitale. Do Dietary Supplements Improve Perceived Health Well-Being? Evidence from Korea. International Journal of Environmental Research and Public Health. 2021; 18 (3):1306.
Chicago/Turabian StyleDonghoon Kim; Inbae Ji; John Ng’Ombe; Kwideok Han; Jeffrey Vitale. 2021. "Do Dietary Supplements Improve Perceived Health Well-Being? Evidence from Korea." International Journal of Environmental Research and Public Health 18, no. 3: 1306.
Donghoon Kim; Inbae Ji; Kwideok Han; John N. Ng'Ombe. Effects of Consumer Characteristics on the Intake of Health Functional Foods: Implications for National Health Expenditure Savings. Food Supplements and Biomaterials for Health 2021, 1, 1 .
AMA StyleDonghoon Kim, Inbae Ji, Kwideok Han, John N. Ng'Ombe. Effects of Consumer Characteristics on the Intake of Health Functional Foods: Implications for National Health Expenditure Savings. Food Supplements and Biomaterials for Health. 2021; 1 ():1.
Chicago/Turabian StyleDonghoon Kim; Inbae Ji; Kwideok Han; John N. Ng'Ombe. 2021. "Effects of Consumer Characteristics on the Intake of Health Functional Foods: Implications for National Health Expenditure Savings." Food Supplements and Biomaterials for Health 1, no. : 1.
Donghoon Kim; Kwideok Han; John N. Ng'Ombe; Seokhyun Heo; Inbae Ji. An Analysis of the Economic Effects of Converting Echinacea Ingredients to Health Functional Foods. Food Supplements and Biomaterials for Health 2021, 1, 1 .
AMA StyleDonghoon Kim, Kwideok Han, John N. Ng'Ombe, Seokhyun Heo, Inbae Ji. An Analysis of the Economic Effects of Converting Echinacea Ingredients to Health Functional Foods. Food Supplements and Biomaterials for Health. 2021; 1 (2):1.
Chicago/Turabian StyleDonghoon Kim; Kwideok Han; John N. Ng'Ombe; Seokhyun Heo; Inbae Ji. 2021. "An Analysis of the Economic Effects of Converting Echinacea Ingredients to Health Functional Foods." Food Supplements and Biomaterials for Health 1, no. 2: 1.
Crop diversification is a climate-smart agricultural technique which helps to improve resilience for farmers in the face of volatile weather due to climate change. Previous research on its effects on technical efficiency has shown mixed results. Despite burgeoning literature on the subject, an important research question that remains uninvestigated is: does crop diversification involve a compromise between technical efficiency and resilience (income stability) for rural farmers? Using nationally representative rural household survey data from Zambia, this study empirically answers this research question. We employ the Data Envelopment Approach (DEA) for efficiency and a two- step least-squares approach for income variability. Our results show evidence that crop diversification significantly improves income stability but significantly reduces technical efficiency. The paper provides useful implications for policies that promote crop diversification in Zambia and other countries.
Agness Mzyece; John N. Ng’Ombe. Does Crop Diversification Involve a Trade-Off Between Technical Efficiency and Income Stability for Rural Farmers? Evidence from Zambia. Agronomy 2020, 10, 1875 .
AMA StyleAgness Mzyece, John N. Ng’Ombe. Does Crop Diversification Involve a Trade-Off Between Technical Efficiency and Income Stability for Rural Farmers? Evidence from Zambia. Agronomy. 2020; 10 (12):1875.
Chicago/Turabian StyleAgness Mzyece; John N. Ng’Ombe. 2020. "Does Crop Diversification Involve a Trade-Off Between Technical Efficiency and Income Stability for Rural Farmers? Evidence from Zambia." Agronomy 10, no. 12: 1875.
China is one of the largest sources of outbound tourists coming to the United States. We used data from a choice experiment to determine whether Chinese tourists are interested and willing to pay for agritourism tour packages in which the U.S. state of Oklahoma is the rural destination. Our research is important because agritourism is a growing source of farm revenue, international tourists have potential to accelerate this growth, and China is the largest market for international tourism. Results suggest that, from various agritourism packages offered to them, Chinese travelers are price conscious but willing to pay significant amounts for packages that provide more local foods, that allow them to visit more event and recreation sites, and stay in cabins rather than farmstead accommodations. We also find evidence of significant heterogeneity in Chinese willingness to pay for agritourism attributes.
Tong Wu; Shida Rastegari Henneberry; John N. Ng’Ombe; Richard T. Melstrom. Chinese Demand for Agritourism in Rural America. Sustainability 2020, 12, 3052 .
AMA StyleTong Wu, Shida Rastegari Henneberry, John N. Ng’Ombe, Richard T. Melstrom. Chinese Demand for Agritourism in Rural America. Sustainability. 2020; 12 (7):3052.
Chicago/Turabian StyleTong Wu; Shida Rastegari Henneberry; John N. Ng’Ombe; Richard T. Melstrom. 2020. "Chinese Demand for Agritourism in Rural America." Sustainability 12, no. 7: 3052.
Maize (Zea mays L.) is one of the commonly grown grain crops and remains a source of staple food and food security for most countries in sub-Saharan Africa (SSA). But climate change threatens agricultural potential in SSA thereby risking food security especially that most maize production is rain-fed in these countries. Thus, numerous studies have examined impacts of climate change on maize production and productivity resulting in several adaption strategies being promoted to mitigate the negative effects of climate change. But to the best of our knowledge, there has not been any studies in literature that provide a review of impacts of climate change on maize production and productivity in SSA. This chapter therefore provides a review of empirical climate change impacts on maize production and its productivity in SSA. We chose SSA because most countries in SSA are underdeveloped and therefore more vulnerable to climate change effects. This is important because this review will provide an easier access of such results for both scholars and policy makers in search of empirical impacts of climate change on maizeproduction and productivity in SSA.
Kelvin Mulungu; John Ng'ombe. Climate Change Impacts on Sustainable Maize Production in Sub-Saharan Africa: A Review. 2020, 1 .
AMA StyleKelvin Mulungu, John Ng'ombe. Climate Change Impacts on Sustainable Maize Production in Sub-Saharan Africa: A Review. . 2020; ():1.
Chicago/Turabian StyleKelvin Mulungu; John Ng'ombe. 2020. "Climate Change Impacts on Sustainable Maize Production in Sub-Saharan Africa: A Review." , no. : 1.
The tobacco epidemic is one of the most prominent public health threats the world has ever faced. Public health policy that seeks to limit the problem may have to target not only the price of tobacco but also the initiation stage in a smoker’s life—the adolescent stage. Most research on teen smoking focuses on initiation and other stories. Moreover, what determines the desire to quit smoking among teens is not well understood, even though planning to quit smoking is an important stage toward successful cessation. This research contributes to healthcare literature by using Bayesian hierarchical techniques, estimated using Hamiltonian Monte Carlo (HMC) and its extension, the No-U-Turn Sampler (NUTS), to empirically identify what drives the intention to quit smoking among teen smokers in Zambia. Results suggest that, among the junior secondary school-going adolescent smokers in Zambia, about 63% have plans to quit smoking. We find socio-demographic characteristics and several tobacco-smoking-related factors as salient drivers of adolescent smokers’ plans to quit smoking. For policymaking, we recommend that school-going teen smokers should have access to smoking cessation aids to help them quit smoking. Most importantly, increased awareness of dangers of smoking, advice by health professionals, stringent public policies on smoking, as well as parental guidance could be useful to help adolescent smokers realize their quitting plans.
John N. Ng’Ombe; N. Rodgers Nedson; Novan F. P. Tembo. “Look at Me, I Plan to Quit Smoking”: Bayesian Hierarchical Analysis of Adolescent Smokers’ Intention to Quit Smoking. Healthcare 2020, 8, 76 .
AMA StyleJohn N. Ng’Ombe, N. Rodgers Nedson, Novan F. P. Tembo. “Look at Me, I Plan to Quit Smoking”: Bayesian Hierarchical Analysis of Adolescent Smokers’ Intention to Quit Smoking. Healthcare. 2020; 8 (2):76.
Chicago/Turabian StyleJohn N. Ng’Ombe; N. Rodgers Nedson; Novan F. P. Tembo. 2020. "“Look at Me, I Plan to Quit Smoking”: Bayesian Hierarchical Analysis of Adolescent Smokers’ Intention to Quit Smoking." Healthcare 8, no. 2: 76.
While climate change threatens global food security, health, and nutrition outcomes, Africa is more vulnerable because its economies largely depend on rain-fed agriculture. Thus, there is need for agricultural producers in Africa to employ robust adaptive measures that withstand the risks of climate change. However, the success of adaptation measures to climate change primarily depends on the communities’ knowledge or awareness of climate change and its risks. Nonetheless, existing empirical research is still limited to illuminate farmers’ awareness of the climate change problem. This study employs a Bayesian hierarchical logistic model, estimated using Hamiltonian Monte Carlo (HMC) methods, to empirically determine drivers of smallholder farmers’ awareness of climate change and its risks to agriculture in Zambia. The results suggest that on average, 77% of farmers in Zambia are aware of climate change and its risks to agriculture. We find socio-demographics, climate change information sources, climate change adaptive factors, and climate change impact-related shocks as predictors of the expression of climate change awareness. We suggest that farmers should be given all the necessary information about climate change and its risks to agriculture. Most importantly, the drivers identified can assist policymakers to provide the effective extension and advisory services that would enhance the understanding of climate change among farmers in synergy with appropriate farm-level climate-smart agricultural practices.
John N. Ng’Ombe; Moses C. Tembo; Blessing Masasi. “Are They Aware, and Why?” Bayesian Analysis of Predictors of Smallholder Farmers’ Awareness of Climate Change and Its Risks to Agriculture. Agronomy 2020, 10, 376 .
AMA StyleJohn N. Ng’Ombe, Moses C. Tembo, Blessing Masasi. “Are They Aware, and Why?” Bayesian Analysis of Predictors of Smallholder Farmers’ Awareness of Climate Change and Its Risks to Agriculture. Agronomy. 2020; 10 (3):376.
Chicago/Turabian StyleJohn N. Ng’Ombe; Moses C. Tembo; Blessing Masasi. 2020. "“Are They Aware, and Why?” Bayesian Analysis of Predictors of Smallholder Farmers’ Awareness of Climate Change and Its Risks to Agriculture." Agronomy 10, no. 3: 376.
The tobacco epidemic is one of the leading public health threats the world has ever faced and public health policy that seeks to limit the problem may not only have to target the price of tobacco but also the initiation stage in a smoker’s life – the adolescent stage. This research contributes to the health economics literature by using a Bayesian hierarchical logistic model, estimated using Hamiltonian Monte Carlo (HMC) methods to empirically identify what drives the intentions to quit smoking among adolescent smokers in Zambia. Results suggest that among the junior secondary school-going adolescent smokers in Zambia, about 63% have plans to quit smoking. We find socio-demographic characteristics and several tobacco-smoking-related factors as the main drivers of adolescent smokers’ plans to quit smoking. Most importantly, we provide insights that could be useful to help adolescent smokers realize their quitting plans.
John N. Ng'ombe; N. Rodgers Nedson; Novan F. P. Tembo. “Look at Me, I Plan to Quit Smoking”: Bayesian Hierarchical Analysis of Adolescent Smokers’ Intention to Quit Smoking. 2020, 1 .
AMA StyleJohn N. Ng'ombe, N. Rodgers Nedson, Novan F. P. Tembo. “Look at Me, I Plan to Quit Smoking”: Bayesian Hierarchical Analysis of Adolescent Smokers’ Intention to Quit Smoking. . 2020; ():1.
Chicago/Turabian StyleJohn N. Ng'ombe; N. Rodgers Nedson; Novan F. P. Tembo. 2020. "“Look at Me, I Plan to Quit Smoking”: Bayesian Hierarchical Analysis of Adolescent Smokers’ Intention to Quit Smoking." , no. : 1.
Corn yields in developing countries are lower than in developed countries partly due to planting methods that involve hand dropping of multiple seeds per hill. Researchers from Oklahoma State University (OSU) recently developed the Greenseeder Hand Planter (GHP) to replace such methods. The first essay determines economic breakeven levels of seed and labor savings, increases in corn yield, and reduced loss of N through reduced ammonia volatilization. Results suggest a $50 GHP used to plant 3 hectares per year would need to increase corn yields on average by about 1.12%, use 12.19% fewer seeds, or reduce labor man-days by 38.66% to equal expected net returns from traditional methods.In the second essay, I conduct Monte Carlo experiments to measure bias in the conditional logit (CL) and independent availability logit (IAL) when there is no choice set formation and when choice sets are stochastically formed. I also compare the performance of the two models using empirical data on paddlefish angler preferences collected in Oklahoma. Both the CL and IAL work well when their own assumptions hold, but not under the alternative’s assumptions. However, the IAL produces unbiased and less efficient parameter estimates when individuals actually choose from the full set of alternatives. Empirical results suggest the IAL is able to predict the attribute-cutoff.To avoid limitations from small-scale agronomic trials, there has been a movement toward large-scale, on-farm field trials but questions remain as how best to conduct them and when it is most profitable to quit them. The third essay addresses these questions by using a fully Bayesian decision-theoretic approach. Data are from Monte Carlo simulations assuming a corn-input stochastic plateau production function. Results suggest the best way to conduct such experiments is to allocate to each of the 10% of the plots, 0 lb. of N, half of N*, and 150% of N* under a 30-plot experimental design. Results further indicate that it optimal to quit such trials in year 2. Sensitivity analysis confirms the optimal quit period but suggests such experiments are most profitable by allocating unalike N levels to all of the 30% of experimental plots.
John Ng'ombe. Economics of the Greenseeder Hand Planter, Discrete Choice Modeling, and On-Farm Field Experimentation. 2019, 1 .
AMA StyleJohn Ng'ombe. Economics of the Greenseeder Hand Planter, Discrete Choice Modeling, and On-Farm Field Experimentation. . 2019; ():1.
Chicago/Turabian StyleJohn Ng'ombe. 2019. "Economics of the Greenseeder Hand Planter, Discrete Choice Modeling, and On-Farm Field Experimentation." , no. : 1.
Bart Niyibizi; John Ng'Ombe; Tracy A. Boyer. Regulating earthquake risk: preferences for trade-offs between economic benefits and regulation of produced wastewater injection from hydraulic fracturing. Journal of Environmental Planning and Management 2019, 63, 981 -1000.
AMA StyleBart Niyibizi, John Ng'Ombe, Tracy A. Boyer. Regulating earthquake risk: preferences for trade-offs between economic benefits and regulation of produced wastewater injection from hydraulic fracturing. Journal of Environmental Planning and Management. 2019; 63 (6):981-1000.
Chicago/Turabian StyleBart Niyibizi; John Ng'Ombe; Tracy A. Boyer. 2019. "Regulating earthquake risk: preferences for trade-offs between economic benefits and regulation of produced wastewater injection from hydraulic fracturing." Journal of Environmental Planning and Management 63, no. 6: 981-1000.
Scientific evidence suggests earthquakes occurring in Oklahoma since 2009 are not “acts of God”, but very likely triggered by wastewater injection in disposal wells by oil and gas (O&G) companies. While sustaining the O&G industry's contribution to the economy is generally important, achieving environmental and public protection may in part rely on how earthquake inducers are held liable for damage. We use a Bayesian Tobit censored model, estimated using Markov Chain Monte Carlo (MCMC) methods to determine factors that influence public preferences for how much liability O&G companies should assume for induced earthquake-related damage. Data are from a survey of Oklahomans collected in 2017 by Survey Sampling International (SSI). Results suggest people would, on average, hold O&G companies liable for 75% of the earthquake damage. We find socio-demographic, earthquake, locational, and O&G industry-related factors as the main drivers of earthquake damage liability. However, their effects on damage liability vary between respondents that have had their property damaged by earthquakes and those that in some way benefit from O&G companies through jobs and gas-leases. We provide insights by which individuals might lobby representatives to impose new liability or regulatory mechanisms on O&G companies to avoid or compensate for earthquake damage.
John N. Ng'Ombe; Tracy A. Boyer. Determinants of earthquake damage liability assignment in Oklahoma: A Bayesian Tobit censored approach. Energy Policy 2019, 131, 422 -433.
AMA StyleJohn N. Ng'Ombe, Tracy A. Boyer. Determinants of earthquake damage liability assignment in Oklahoma: A Bayesian Tobit censored approach. Energy Policy. 2019; 131 ():422-433.
Chicago/Turabian StyleJohn N. Ng'Ombe; Tracy A. Boyer. 2019. "Determinants of earthquake damage liability assignment in Oklahoma: A Bayesian Tobit censored approach." Energy Policy 131, no. : 422-433.
Smallholder irrigation schemes potentially improve the livelihoods of rural communities in developing countries. However, they face challenges such as infrastructural decline, lack of funding, lack of markets, shortage of water, underutilization of land, and inefficient irrigation systems. In Zimbabwe, the government carried out rehabilitation programs to address these problems but the performance of smallholder irrigation schemes remained poor. These chronic challenges triggered experts to adopt a market systems approach (MSA) to revitalize failing irrigation schemes. Using primary and secondary data sources collected in 2015, this study used a “before” and “after” descriptive assessment approach to determine the effectiveness of the MSA at revitalizing smallholder irrigation schemes in Zimbabwe. We used Mutema Irrigation Scheme as a case study. Results suggest that the MSA leads to improved efficiency of irrigation infrastructure, farm gross margins, willingness to pay irrigation fees and farmers’ standard of living. While this research does not econometrically establish causation of relations between variables involved, our results provide a foundation for future research on the application of the MSA to revitalize underperforming smallholder irrigation schemes in developing countries.
Blessing Masasi; John N. Ng’Ombe. Does A Market Systems Approach Revitalize Smallholder Irrigation Schemes? Evidence from Zimbabwe. Sustainable Agriculture Research 2019, 8, p36 .
AMA StyleBlessing Masasi, John N. Ng’Ombe. Does A Market Systems Approach Revitalize Smallholder Irrigation Schemes? Evidence from Zimbabwe. Sustainable Agriculture Research. 2019; 8 (2):p36.
Chicago/Turabian StyleBlessing Masasi; John N. Ng’Ombe. 2019. "Does A Market Systems Approach Revitalize Smallholder Irrigation Schemes? Evidence from Zimbabwe." Sustainable Agriculture Research 8, no. 2: p36.
Corn (Zea mays L.) yields in developing countries are lower than in developed countries, in part due to planting methods that involve hand dropping of multiple seeds per hill. The Greenseeder hand planter (GHP) was developed to reduce seeding rates and long-term health risks from using bare hands to drop pesticide-treated seeds. When used to apply fertilizer, it can prevent loss of N from ammonia volatilization. This research determines economic break-even levels of seed and labor savings, increases in corn yield, and reduced loss of N through reduced ammonia volatilization. A GHP used to plant 3 ha yr–1 that costs US$50 would need to increase corn yields on average by about 1.12%, use 12.19% fewer seeds, or reduce labor man-days by 38.66% to equal expected net returns from traditional methods. Using the GHP to apply fertilizer would on average increase corn yields up to 10.82% ha–1 due to reduced N loss from ammonia volatilization and thus fertilization alone could be enough to pay for the planter. Copyright © 2019. . © 2019 The Author(s).
John N. Ng’Ombe; B. Wade Brorsen; William R. Raun; Jagman S. Dhillon. Economics of the Greenseeder Hand Planter. Agrosystems, Geosciences & Environment 2019, 2, 1 -7.
AMA StyleJohn N. Ng’Ombe, B. Wade Brorsen, William R. Raun, Jagman S. Dhillon. Economics of the Greenseeder Hand Planter. Agrosystems, Geosciences & Environment. 2019; 2 (1):1-7.
Chicago/Turabian StyleJohn N. Ng’Ombe; B. Wade Brorsen; William R. Raun; Jagman S. Dhillon. 2019. "Economics of the Greenseeder Hand Planter." Agrosystems, Geosciences & Environment 2, no. 1: 1-7.
We determine and compare technical efficiency (TE), technology gap ratios (TGRs) and meta-frontier technical efficiency (MTEs) of maize production between regions using nationally representative panel data collected from 4001 smallholder farm households in Zambia. We estimate the stochastic meta-frontier and region-specific stochastic frontiers based on the ‘true random effects’ framework. Our results show variations in efficiency measures and that smallholder maize production is characterised by increasing returns to scale across all regions, which clearly suggest maize farmers to reduce their average long-term costs by increasing their production scale. We find that some regions are on average more technically efficient than others while those with TE values exceeding 90 per cent operate further below their potential output than those with moderate TE values. Similarly, farm households from regions whose mean TE values are about 90 per cent employ inferior farming techniques to those employed by farmers from regions whose mean TE values are lower. This is in part due to industry-wide specific environmental factors. Most importantly, we find no region to have maize farmers that adopt the most advanced techniques. Results further indicate that all provinces have had either lower or higher TEs, TGRs and MTEs in one period than in another. Generally, our results point to the need to promote superior techniques that would withstand industry-wide specific environmental factors. While it is not possible to find the many reasons for wide variations in TEs, TGRs, and MTEs across regions and time, our results make novel contributions to literature.
John N. Ng’Ombe. Technical efficiency of smallholder maize production in Zambia: a stochastic meta-frontier approach. Agrekon 2017, 56, 347 -365.
AMA StyleJohn N. Ng’Ombe. Technical efficiency of smallholder maize production in Zambia: a stochastic meta-frontier approach. Agrekon. 2017; 56 (4):347-365.
Chicago/Turabian StyleJohn N. Ng’Ombe. 2017. "Technical efficiency of smallholder maize production in Zambia: a stochastic meta-frontier approach." Agrekon 56, no. 4: 347-365.