The Experts below are selected from a list of 345 Experts worldwide ranked by ideXlab platform
Eoin Reeves - One of the best experts on this subject based on the ideXlab platform.
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understanding ppp tendering periods in canada a Duration Analysis
Public Performance & Management Review, 2019Co-Authors: Carter B Casady, Darragh Flannery, Richard R Geddes, Dónal Palcic, Eoin ReevesAbstract:AbstractPublic-private partnerships (PPPs) often require lengthy tendering periods that can deter bidders, reduce competition for contracts, and undermine the overall social benefits of PPP procure...
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the determinants of tendering periods for ppp procurement in the uk an empirical Analysis
Applied Economics, 2017Co-Authors: Eoin Reeves, Darragh Flannery, Dónal Palcic, Richard R GeddesAbstract:ABSTRACTThe procurement of infrastructure projects via public–private partnerships (PPPs) is rising globally. PPPs are, however, often characterized by lengthy tendering periods, defined as the difference between contract notice and financial close. Tendering periods are important because they account for a significant proportion of overall project delivery time. Slow tendering deters bidders and thus reduces competition for contracts. We source data on 670 PPP projects in the United Kingdom and use a Duration Analysis model to empirically examine factors that impact tendering period Duration. Our results reveal significant sectoral variation with projects in the health and housing sectors taking significantly longer to reach financial close. We also show that, after controlling for other factors, projects with higher capital values and projects that overlap with the timing of general elections are associated with significantly longer tendering periods. We further examine the impact of the competitive dia...
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ppp procurement in ireland an Analysis of tendering periods
Local Government Studies, 2015Co-Authors: Eoin Reeves, Dónal Palcic, Darragh FlanneryAbstract:AbstractThe relative complexity of procurement under public–private partnership (PPP) means that tendering periods can be longer compared to traditional procurement models. Reducing the tendering period is therefore an important challenge if PPP is to deliver infrastructure on time and within budget. Using data from 59 PPP projects in Ireland we find that the average tendering period has been 34 months. Analysis using Duration Analysis shows that tendering periods have fallen over time and are positively but not strongly associated with the capital value of projects. Tendering periods are longer for projects that do not involve private finance with the majority of such projects procured by local authorities. We use two case studies of PPP procurement to explore these issues further. Both cases highlight the complex array of factors that can impact on tendering periods some of which are outside the control of the procurement authority.
Vangelis Tzouvelekas - One of the best experts on this subject based on the ideXlab platform.
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information transmission in irrigation technology adoption and diffusion social learning extension services and spatial effects
American Journal of Agricultural Economics, 2014Co-Authors: Margarita Genius, Phoebe Koundouri, Celine Nauges, Vangelis TzouvelekasAbstract:In this article, we investigate the role of information transmission in promoting agricultural technology adoption and diffusion through extension services and social learning. We develop a theoretical model of technology adoption and diffusion, which we then empirically apply, using Duration Analysis, on a micro-dataset consisting of recall data covering the period 1994-2004 for olive-producing farms from Crete, Greece. Our findings suggest that both extension services and social learning are strong determinants of technology adoption and diffusion, while the effectiveness of each of the two informational channels is enhanced by the presence of the other.
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information transmission in irrigation technology adoption and diffusion social learning extension services and spatial effects
2013Co-Authors: Margarita Genius, Phoebe Koundouri, Celine Nauges, Vangelis TzouvelekasAbstract:In this article, we investigate the role of information transmission in promoting agricultural technology adoption and diffusion through extension services and social learning. We develop a theoretical model of technology adoption and diffusion, which we then empirically apply, using Duration Analysis, on a micro-dataset consisting of recall data covering the period 1994-2004 for olive-producing farms from Crete, Greece. Our findings suggest that both extension services and social learning are strong determinants of technology adoption and diffusion, while the effectiveness of each of the two informational channels is enhanced by the presence of the other. (This abstract was borrowed from another version of this item.)
Darragh Flannery - One of the best experts on this subject based on the ideXlab platform.
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understanding ppp tendering periods in canada a Duration Analysis
Public Performance & Management Review, 2019Co-Authors: Carter B Casady, Darragh Flannery, Richard R Geddes, Dónal Palcic, Eoin ReevesAbstract:AbstractPublic-private partnerships (PPPs) often require lengthy tendering periods that can deter bidders, reduce competition for contracts, and undermine the overall social benefits of PPP procure...
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the determinants of tendering periods for ppp procurement in the uk an empirical Analysis
Applied Economics, 2017Co-Authors: Eoin Reeves, Darragh Flannery, Dónal Palcic, Richard R GeddesAbstract:ABSTRACTThe procurement of infrastructure projects via public–private partnerships (PPPs) is rising globally. PPPs are, however, often characterized by lengthy tendering periods, defined as the difference between contract notice and financial close. Tendering periods are important because they account for a significant proportion of overall project delivery time. Slow tendering deters bidders and thus reduces competition for contracts. We source data on 670 PPP projects in the United Kingdom and use a Duration Analysis model to empirically examine factors that impact tendering period Duration. Our results reveal significant sectoral variation with projects in the health and housing sectors taking significantly longer to reach financial close. We also show that, after controlling for other factors, projects with higher capital values and projects that overlap with the timing of general elections are associated with significantly longer tendering periods. We further examine the impact of the competitive dia...
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ppp procurement in ireland an Analysis of tendering periods
Local Government Studies, 2015Co-Authors: Eoin Reeves, Dónal Palcic, Darragh FlanneryAbstract:AbstractThe relative complexity of procurement under public–private partnership (PPP) means that tendering periods can be longer compared to traditional procurement models. Reducing the tendering period is therefore an important challenge if PPP is to deliver infrastructure on time and within budget. Using data from 59 PPP projects in Ireland we find that the average tendering period has been 34 months. Analysis using Duration Analysis shows that tendering periods have fallen over time and are positively but not strongly associated with the capital value of projects. Tendering periods are longer for projects that do not involve private finance with the majority of such projects procured by local authorities. We use two case studies of PPP procurement to explore these issues further. Both cases highlight the complex array of factors that can impact on tendering periods some of which are outside the control of the procurement authority.
Yuanzhen Ren - One of the best experts on this subject based on the ideXlab platform.
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observation Duration Analysis for earth surface features from a moon based platform
Advances in Space Research, 2018Co-Authors: Hanlin Ye, Guang Liu, Huadong Guo, Yuanzhen RenAbstract:Abstract Earth System Science is a discipline that performs holistic and comprehensive research on various components of the Earth. One of a key issue for the Earth monitoring and observation is to enhance the observation Duration, the time intervals during which the Earth surface features can be observed by sensors. In this work, we propose to utilise the Moon as an Earth observation platform. Thanks to the long distance between the Earth and the Moon, and the vast space on the lunar surface which is suitable for sensor installation, this Earth observation platform could have large spatial coverage, long temporal Duration, and could perform multi-layer detection of the Earth. The line of sight between a proposed Moon-based platform and the Earth will change with different lunar surface positions; therefore, in this work, the position of the lunar surface was divided into four regions, including one full observation region and three incomplete observation regions. As existing methods are not able to perform global-scale observations, a Boolean matrix method was established to calculate the necessary observation Durations from a Moon-based platform. Based on Jet Propulsion Laboratory (JPL) ephemerides and Earth Orientation Parameters (EOP), a formula was developed to describe the geometrical relationship between the Moon-based platform and Earth surface features in the unified spatial coordinate system and the unified time system. In addition, we compared the observation geometries at different positions on the lunar surface and two parameters that are vital to observation Duration calculations were considered. Finally, an Analysis method was developed. We found that the observation Duration of a given Earth surface feature shows little difference regardless of sensor position within the full observation region. However, the observation Duration for sensors in the incomplete observation regions is reduced by at least half. In summary, our results demonstrate the suitability of a Moon-based platform located in the full observation region.
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observation Duration Analysis for earth surface features from a moon based platform
Advances in Space Research, 2018Co-Authors: Hanlin Ye, Guang Liu, Huadong Guo, Yuanzhen RenAbstract:Abstract Earth System Science is a discipline that performs holistic and comprehensive research on various components of the Earth. One of a key issue for the Earth monitoring and observation is to enhance the observation Duration, the time intervals during which the Earth surface features can be observed by sensors. In this work, we propose to utilise the Moon as an Earth observation platform. Thanks to the long distance between the Earth and the Moon, and the vast space on the lunar surface which is suitable for sensor installation, this Earth observation platform could have large spatial coverage, long temporal Duration, and could perform multi-layer detection of the Earth. The line of sight between a proposed Moon-based platform and the Earth will change with different lunar surface positions; therefore, in this work, the position of the lunar surface was divided into four regions, including one full observation region and three incomplete observation regions. As existing methods are not able to perform global-scale observations, a Boolean matrix method was established to calculate the necessary observation Durations from a Moon-based platform. Based on Jet Propulsion Laboratory (JPL) ephemerides and Earth Orientation Parameters (EOP), a formula was developed to describe the geometrical relationship between the Moon-based platform and Earth surface features in the unified spatial coordinate system and the unified time system. In addition, we compared the observation geometries at different positions on the lunar surface and two parameters that are vital to observation Duration calculations were considered. Finally, an Analysis method was developed. We found that the observation Duration of a given Earth surface feature shows little difference regardless of sensor position within the full observation region. However, the observation Duration for sensors in the incomplete observation regions is reduced by at least half. In summary, our results demonstrate the suitability of a Moon-based platform located in the full observation region.
Jaap H Abbring - One of the best experts on this subject based on the ideXlab platform.
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the unobserved heterogeneity distribution in Duration Analysis
Biometrika, 2007Co-Authors: Jaap H Abbring, Gerard J. Van Den BergAbstract:In a large class of hazard models with proportional unobserved heterogeneity, the distribution of the heterogeneity among survivors converges to a gamma distribution. This convergence is often rapid. We derive this result as a general result for exponential mixtures and explore its implications for the specification and empirical Analysis of univariate and multivariate Duration models.
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the unobserved heterogeneity distribution in Duration Analysis
Biometrika, 2007Co-Authors: Jaap H Abbring, Gerard J Van Den BergAbstract:jabbringgfeweb.vu.nl gberggfeweb.vu.nl SUMMARY In a large class of hazard models with proportional unobserved heterogeneity, the distribution of the heterogeneity among survivors converges to a gamma distribution. This convergence is often rapid. We derive this result as a general result for exponential mixtures and explore its implications for the specification and empirical Analysis of univariate and multivariate Duration models.
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the unobserved heterogeneity distribution in Duration Analysis
Research Papers in Economics, 2006Co-Authors: Jaap H Abbring, Gerard J Van Den BergAbstract:In a large class of hazard models with proportional unobserved heterogeneity, the distribution of the heterogeneity among survivors converges to a gamma distribution. This convergence is often rapid. We derive this result as a general result for exponential mixtures and explore its implications for the specification and empirical Analysis of univariate and multivariate Duration models. This discussion paper resulted in a publication in Biometrika .
