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  • 1
    Electronic Resource
    Electronic Resource
    The paradox of drowned carbonate platforms and the origin of Cretaceous Pacific guyots (1998)
    [s.l.] : Macmillan Magazines Ltd.
    Nature 392 (1998), S. 889-894 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Geochemical, stratigraphic and palaeolatitudinal data from deep boreholes drilled through Pacific guyots—flat-topped seamounts—help to explain the drowning of these Cretaceous shallow-water carbonate platforms that once thrived through the accumulation of biogenic and inorganic ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/31865
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  • 2
    Electronic Resource
    Electronic Resource
    Statistical Inference in Nonparametric Frontier Models: The State of the Art (2000)
    Springer
    Journal of productivity analysis 13 (2000), S. 49-78 
    Details
    ISSN: 1573-0441
    Keywords: DEA ; FDH ; Nonparametric estimation ; Efficiency ; Frontier models ; Bootstrapping
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Efficiency scores of firms are measured by their distance to an estimated production frontier. The economic literature proposes several nonparametric frontier estimators based on the idea of enveloping the data (FDH and DEA-type estimators). Many have claimed that FDH and DEA techniques are non-statistical, as opposed to econometric approaches where particular parametric expressions are posited to model the frontier. We can now define a statistical model allowing determination of the statistical properties of the nonparametric estimators in the multi-output and multi-input case. New results provide the asymptotic sampling distribution of the FDH estimator in a multivariate setting and of the DEA estimator in the bivariate case. Sampling distributions may also be approximated by bootstrap distributions in very general situations. Consequently, statistical inference based on DEA/FDH-type estimators is now possible. These techniques allow correction for the bias of the efficiency estimators and estimation of confidence intervals for the efficiency measures. This paper summarizes the results which are now available, and provides a brief guide to the existing literature. Emphasizing the role of hypotheses and inference, we show how the results can be used or adapted for practical purposes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007864806704
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  • 3
    Electronic Resource
    Electronic Resource
    Detecting influential observations in data envelopment analysis (1995)
    Springer
    Journal of productivity analysis 6 (1995), S. 27-45 
    Details
    ISSN: 1573-0441
    Keywords: DEA ; influential observations ; outliers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This paper provides diagnostic tools for examining the role of influential observations in Data Envelopment Analysis (DEA) applications. Observations may be prioritized for further scrutiny to see if they are contaminated by data errors; this prioritization is important in situations where data-checking is costly and resources are limited. Several empirical examples are provided using data from previously published studies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01073493
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  • 4
    Electronic Resource
    Electronic Resource
    Of Course We Can Bootstrap DEA Scores! But Does It Mean Anything? Logic Trumps Wishful Thinking (1999)
    Springer
    Journal of productivity analysis 11 (1999), S. 93-97 
    Details
    ISSN: 1573-0441
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007739507007
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  • 5
    Electronic Resource
    Electronic Resource
    Decomposing hospital productivity changes, 1985–1988: A nonparametric Malmquist approach (1995)
    Springer
    Journal of productivity analysis 6 (1995), S. 343-363 
    Details
    ISSN: 1573-0441
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract Annual data on U.S. hospitals from 1985–1988 are evaluated by ownership type—profit, nonprofit, state and local government, and U.S. Department of Veterans Affairs (VA)—for changes in hospital productivity over time. Distance functions are used to measure Malmquist indices of productivity change, which are then decomposed into indices of efficiency change and technology change. In contrast to previous studies using this approach, we allow for variable returns to scale and use both input and output orientations. We find that changes in technology dominate changes in inefficiency in determining changes in productivity.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01073525
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  • 6
    Electronic Resource
    Electronic Resource
    Comparing mean efficiency and productivity scores from small samples: A bootstrap methodology (1995)
    Springer
    Journal of productivity analysis 6 (1995), S. 137-152 
    Details
    ISSN: 1573-0441
    Keywords: Bootstrap ; Data Envelopment Analysis ; fixed and random effects ; Malmquist index ; productivity measurement ; small sample ; panel data
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This paper provides a bootstrap methodology for constructing confidence intervals for means of DEA and econometrically estimated efficiency scores, Malmquist productivity indices, and other similar measures in small samples. The procedure is nonparametric since no distributional assumptions are required. An empirical example is provided.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01073408
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  • 7
    Electronic Resource
    Electronic Resource
    Some Problems with the Ferrier/Hirschberg Bootstrap Idea (1999)
    Springer
    Journal of productivity analysis 11 (1999), S. 67-80 
    Details
    ISSN: 1573-0441
    Keywords: DEA ; Bootstrap ; Efficiency ; Frontier ; Nonparametric
    Source: Springer Online Journal Archives 1860-2000
    Topics: Economics
    Notes: Abstract This paper demonstrates that the bootstrap procedure suggested by Ferrier and Hirschberg (1997) gives inconsistent estimates. A very simple example is given to illustrate the statistical issues underlying nonparametric efficiency measurement and the problems with the Ferrier/Hirschberg approach, and may serve as a primer on bootstrapping in nonparametric models of production processes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1007735422028
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  • 8
    Electronic Resource
    Electronic Resource
    Floral constancy in bumble bees: handling efficiency or perceptual conditioning? (1996)
    Springer
    Oecologia 106 (1996), S. 493-499 
    Details
    ISSN: 1432-1939
    Keywords: Bombus vagans ; Conditioning ; Constancy ; Handling ; Pollination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Individual bees often prefer flowers of the same species that they are already foraging on, and other individual bees prefer other flowers. This “floral constancy” has classically been explained as a learned behavior by which bees avoid wasting time switching between handling techniques. Choice trails were given to Bombus vagans workers that were freely foraging in mixed and pure fields of Trifolium pratense, T. repens, Viccia cracca, and Prunella vulgaris. Contrary to expectation, (1) bees showed if anything a stronger preference for their flower type in pure fields where they lacked experience than in a mixed field where they had had the opportunity to learn, (2) there was greater constancy in a mixed field of the two morphologically similar Trifolium species than in a mixed field of the morphologically disparate T. pratense and P. vulgaris, and (3) bees were more willing to switch between flowers of distinct morphologies when the colors were similar than between flowers of distinct colors when the morphologies were similar. We suggest that constancy is due to some form of perceptual conditioning whereby individual bees become temporarily sensitized to one or a few floral cues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00329707
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  • 9
    Electronic Resource
    Electronic Resource
    The Economics of Agriculture in the Maricopa-Stanfield Irrigation and Drainage District in Central Arizona (2000)
    Springer
    Irrigation and drainage systems 14 (2000), S. 121-138 
    Details
    ISSN: 1573-0654
    Keywords: economics ; irrigated agriculture ; irrigation district ; interdependencies
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The economic performance of a Central Arizona Projectirrigation district is determined by the economiccondition of the growers the district serves and theunderlying financial structure of the district. Inthe case of the Maricopa-Stanfield Irrigation andDrainage District, adverse economic conditions in theagricultural sector and a high debt obligationrelative to water sales called into question thefinancial sustainability of the district. Districtmanagement took positive steps, like the ManagementImprovement Program (MIP) and departmentrestructuring, to improve the economic performance ofthe water delivery system. These actions relied onthe shared understanding of the waterinterdependencies between agricultural and urban userswhich was obtained through the Diagnostic Analysis ofthe MIP.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1006249822234
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  • 10
    Electronic Resource
    Electronic Resource
    Variation in the intensity of pollination inDrosera tracyi: Selection is strongest when resources are intermediate (1995)
    Springer
    Evolutionary ecology 9 (1995), S. 382-396 
    Details
    ISSN: 1573-8477
    Keywords: Drosera tracyi ; natural selection ; pollination ; resource levels
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary I propose that the strength of selection is greatest when resource levels are intermediate. This idea was partially tested using artificial character variation for petal size inDrosera tracyi. This plant opens one flower each morning, with stigmas becoming available and pollen being presented simultaneously throughout the population. Bees remove all the pollen that can be removed and deposit all the pollen that can be deposited in one or two visits. Visitation rates track blooming density, as do pollen removal and deposition. I measured selection as the difference in pollen removal and deposition between flowers with trimmed petals versus flowers with normal petals. In one meadow, I found a wide range of levels of pollination and corresponding levels of selection, and selection was strongest at intermediate levels of pollination. This might mean that organisms are adapted to conditions when resources are at intermediate levels even though they may experience those conditions relatively rarely.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01237761
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