14 research outputs found

    On the Accuracy of Bootstrap Confidence Intervals for Efficiency Levels in Stochastic Frontier Models with Panel Data

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    We study the construction of confidence intervals for efficiency levels of individual firms in stochastic frontier models with panel data. The focus is on bootstrapping and related methods. We start with a survey of various versions of the bootstrap. We also propose a simple parametric alternative in which one acts as if the identity of the best firm is known. Monte Carlo simulations indicate that the parametric method works better than the per- centile bootstrap, but not as well as bootstrap methods that make bias corrections. All of these methods are valid only for large time-series sample size (T), and correspondingly none of the methods yields very accurate confidence intervals except when T is large enough that the identity of the best firm is clear. We also present empirical results for two well-known data sets.Stochastic frontier, bootstrap, efficiency

    Multiple frequencies multiple carriers

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    The OFDM scheme has the problems of out-of-band (OOB) leakage and low transmission efficiency in the time domain. This is because the scheme is a single frequency single carrier one in which one carrier is generated by one frequency. To overcome the problems we propose multiple frequencies multiple carriers (MFMC) scheme in which one carrier is generated using many frequencies. We establish a practical model which not only eliminates these disadvantages but also improves the transmission efficiency and peak-to-average power ratio (PAPR) performance. In the proposed MFMC scheme, the filter matrix is used in order to confine the OOB leakage of the spectrums of transmit signal, which is generated through processes such as jump-removing, filtering, and orthogonalizing from an initial matrix. MFMS is evaluated compared with OFDM in view of transmission efficiency, OOB leakage, and bit error rate performance

    Valid tests of whether technical inefficiency depends on firm characteristics

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    We wish to test whether technical inefficiency depends on observable characteristics of the firm. We consider a two-step procedure in which the second step is a regression of estimated inefficiency on firm characteristics. A valid test of the hypothesis of no effect requires an adjustment to the variance matrix of the estimates. Unfortunately the adjustment is not distribution-free. We show that this test is the LM test in the exponential case. We also consider tests based on nonlinear least squares, which do not require a distributional assumption. The size and power of these tests are examined in simulations.

    Multiple frequencies multiple carriers

    No full text
    The OFDM scheme has the problems of out-of-band (OOB) leakage and low transmission efficiency in the time domain. This is because the scheme is a single frequency single carrier one in which one carrier is generated by one frequency. To overcome the problems we propose multiple frequencies multiple carriers (MFMC) scheme in which one carrier is generated using many frequencies. We establish a practical model which not only eliminates these disadvantages but also improves the transmission efficiency and peak-to-average power ratio (PAPR) performance. In the proposed MFMC scheme, the filter matrix is used in order to confine the OOB leakage of the spectrums of transmit signal, which is generated through processes such as jump-removing, filtering, and orthogonalizing from an initial matrix. MFMS is evaluated compared with OFDM in view of transmission efficiency, OOB leakage, and bit error rate performance

    Political influence on historical ESA listings by state: a count data analysis

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    Endangered Species Act listings, League of Conservation Voters’ environmental scores, NatureServe “at-risk” assessment, Count data analysis, U.S. House of Representatives, U.S. Senate, U.S. Fish & Wildlife Service, Q28, Q20, Q29, K32, H41,
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