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Xian Zhou - One of the best experts on this subject based on the ideXlab platform.

  • Modeling gap times between recurrent events by Marginal Rate function
    Computational Statistics & Data Analysis, 2012
    Co-Authors: Xiaobing Zhao, Xian Zhou
    Abstract:

    Gap times between recurrent events are often encountered in longitudinal follow-up studies related to medical science, biostatistics, econometrics, reliability, criminology, demography, and other areas. There have been many models to fit such data, such as proportional hazards (PH) model and additive hazards (AH) model, among others. Standard partial likelihood can be employed to draw their statistical inference. The inference from a direct PH or AH assumption on the gap times, however, is less intuitive and straightforward than Marginal Rate models-which are often preferred by practitioners due to their more direct interpretations for identifying risk factors. In addition, the existing models have not adequately considered zero-recurrence subjects often encountered in recurrent event data. To overcome these shortcomings, we propose an alternative gap time model using an additive Marginal Rate function that accounts for zero-recurrence subjects. Local profile-likelihood is applied to estimate the model attributes, and the asymptotic properties of the estimators are established as well. The performance of the proposed estimators is evaluated by a simulation study. The proposed model is applied to analyze a set of data on pulmonary exacerbations and rhDNase treatment.

Zhouxian - One of the best experts on this subject based on the ideXlab platform.

Toshiyuki Sueyoshi - One of the best experts on this subject based on the ideXlab platform.

  • Marginal Rate of Transformation and Rate of Substitution measured by DEA environmental assessment: Comparison among European and North American nations
    Energy Economics, 2016
    Co-Authors: Toshiyuki Sueyoshi, Yan Yuan
    Abstract:

    This study discusses the new use of DEA (Data Envelopment Analysis) environmental assessment to measure MRT (Marginal Rate of Transformation) and RS (Rate of Substitution) among production factors (e.g., inputs, desirable and undesirable outputs). To measure the degree on MRT and RS, this study first examines a concept of disposability from the perspective of economic stRategies to combat various environmental issues. The stRategies are extendable to a policy change for pollution prevention. The underlying concept is sepaRated into natural and managerial disposability. Under managerial disposability, it is possible for us to measure an occurrence of desirable congestion, or eco-technology innovation. Considering the disposability concept, this study discusses how to measure the type and magnitude of MRT and RS. A problem of the MRT & RS measurement is that these measures usually become unstable (e.g., very large or small in these magnitudes) because DEA does not assume any functional form for economic activities. To overcome such a difficulty, this study equips DEA environmental assessment with multiplier restriction by utilizing a unique feature on a proposed data treatment. The multiplier restriction in DEA has been never explored in previous works on environmental assessment. In an application, this study finds three important economic concerns on Europe and North America. First, Western Europe outperforms Eastern Europe and North America in their unified efficiency measures under managerial disposability. This study statistically confirms a difference between Western and Eastern Europe, but not between Western Europe and North America. This result exhibits that Eastern Europe is not yet well developed at the level of the other two regions. Second, Eastern Europe has exhibited MRT estimates that are different from Western Europe and North America. The nations in Eastern Europe have an economic potential for industrial developments because the level of their industrial pollutions is less than that of the other two regions. The potential is also found in their MRT estimates. Finally, an interesting difference can be found in the RS estimate between Eastern Europe and Western Europe from 2008 to 2012. They have statistically exhibited a difference between the two regimes, but not with North America. This is because most nations in both Western Europe and North America have already attained a high level of economic successes so that they have a limited industrial potential under current production technology and eco-technology. The situation of the two regions will be changed along with new technology development. In contrast, Eastern Europe is different from the other two regions in terms of attaining such a level of social sustainability because of limited capital accumulation and limited opportunity for technology innovation.

  • Returns to Scale, Damages to Scale, Marginal Rate of Transformation and Rate of Substitution in DEA Environmental Assessment
    Energy Economics, 2012
    Co-Authors: Toshiyuki Sueyoshi, Mika Goto
    Abstract:

    This study discusses a new use of DEA (Data Envelopment Analysis) environmental assessment to measure MRT (Marginal Rate of Transformation) and RS (Rate of Substitution) between desirable and undesirable outputs. To discuss MRT and RS, this study first examines a concept of disposability from the perspective of corpoRate stRategies to adapt a regulation change on undesirable outputs. The concept of disposability is sepaRated into natural and managerial disposability. Then, this study explores the computational framework of RTS (Returns to Scale) and DTS (Damages to Scale). The type of RTS is measured within the natural disposability, while the type of DTS is measured within the managerial disposability. Considering the two types of disposability, this study discusses MRT and RS between desirable and undesirable outputs. As an illustrative example, this study applies the proposed approach to evaluate the performance of US coal-fired power plants. This study finds that the regulation policy on NOx and SO2 has been effective on their emission controls under US Clean Air Act (CAA). The regulation on CO2, or a major source of the global warming and climate change, is still insufficient in the United States. Therefore, this study recommends that US federal and local governments should regulate the amount of CO2 emission under the CAA.

Vicente G. Cancho - One of the best experts on this subject based on the ideXlab platform.

  • A gap time model based on a multiplicative Marginal Rate function that accounts for zero-recurrence units.
    Statistical methods in medical research, 2017
    Co-Authors: Francisco Louzada, Márcia A. C. Macera, Vicente G. Cancho
    Abstract:

    In this article, we propose an alternative gap time model based on a multiplicative Marginal Rate function, which is formulated considering each gap time conditional on the previous recurrence times. In this formulation, the gap times are treated equally and the relation between successive events is no longer a problem. Furthermore, this article considers the inclusion of a proportion of zero-recurrence units (for which the event of interest will not occur) into the model to analyze recurrent event data. Inference aspects of the proposed model are discussed through maximum likelihood approach. A simulation study is carried out to examine the performance of the estimation procedure. The model is applied to hospital readmission data among colorectal cancer patients.

Xiaobing Zhao - One of the best experts on this subject based on the ideXlab platform.

  • Modeling gap times between recurrent events by Marginal Rate function
    Computational Statistics & Data Analysis, 2012
    Co-Authors: Xiaobing Zhao, Xian Zhou
    Abstract:

    Gap times between recurrent events are often encountered in longitudinal follow-up studies related to medical science, biostatistics, econometrics, reliability, criminology, demography, and other areas. There have been many models to fit such data, such as proportional hazards (PH) model and additive hazards (AH) model, among others. Standard partial likelihood can be employed to draw their statistical inference. The inference from a direct PH or AH assumption on the gap times, however, is less intuitive and straightforward than Marginal Rate models-which are often preferred by practitioners due to their more direct interpretations for identifying risk factors. In addition, the existing models have not adequately considered zero-recurrence subjects often encountered in recurrent event data. To overcome these shortcomings, we propose an alternative gap time model using an additive Marginal Rate function that accounts for zero-recurrence subjects. Local profile-likelihood is applied to estimate the model attributes, and the asymptotic properties of the estimators are established as well. The performance of the proposed estimators is evaluated by a simulation study. The proposed model is applied to analyze a set of data on pulmonary exacerbations and rhDNase treatment.