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Two elements enter the choice between 2 and 3SLS for full-system estimation: statistical efficiency and computational cost. 2SLS always has the computational edge, but 3SLS can be more efficient, a relative advantage that increases with the strength of the interrelations among the error terms. A measure of these interrelations is thus helpful in making the choice, and, when there are only two equations, this has suggested using a high pairwise error correlation as an indicator of when to use 3SLS. In larger systems of equations, however, these pairwise correlations can remain small even though more general interrelations give 3SLS the relative advantage. More general indicators are therefore needed, and this paper suggests three such and demonstrates their efficacy.Professor of Economics, Boston College, and Principal Research Associate, Center for Computational Research in Economics and Management Science, MIT. All computation was done on the TROLL system at MIT. My thanks go to Josh Charap for his able research assistance. This research was sponsored in part by the National Science Foundation under grant #IST-8420614. 相似文献
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Paul Camion Bernard Courteau Philippe Delsarte 《Applicable Algebra in Engineering, Communication and Computing》1992,2(3):147-162
The concept of the combinatorial matrix of an unrestricted code and the notion of anr-partition design admitted by a code are introduced and discussed in detail. The theory includes a characterization of completely regular codes, and a combinatorial interpretation of the fact that the distinct rows of the distance distribution matrix of a code are linearly independent. In general, it is possible to compute the distance distribution matrix of any code admitting a given partition design by solving a well-defined system of linear equations; this is an efficient technique provided the number of classes in the partition is relatively small. 相似文献
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The application of irradiation in silicon crystal is introduced.The defects caused by irradiation are reviewed and some major ways of studying defects in irradiated silicon are summarized.Furthermore the problems in the investigation of irradiated silicon are discussed as well as its properties. 相似文献
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A general variance predictor for Cavalieri slices 总被引:1,自引:0,他引:1
L. M. CRUZ-ORIVE 《Journal of microscopy》2006,222(3):158-165
A general variance predictor is presented for a Cavalieri design with slices of an arbitrary thickness t ≥ 0. So far, prediction formulae have been available either for measurement functions with smoothness constant q = 0, 1, … , and t ≥ 0, or for fractional q ∈ [0, 1] with t = 0. Because the possibility of using a fractional q adds flexibility to the variance prediction, we have extended the latter for any q ∈ [0, 1] and t ≥ 0. Empirical checks with previously published human brain data suggest an improved performance of the new prediction formula with respect to the hitherto available ones. 相似文献
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This article is concerned with the l2-approximation of a given transfer function f by a rational one whose order is prescribed. We show that the sum of the indices of the critical points of the criterion is generically equal to 1, and in particular does not depend on f. 相似文献
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