Are Hordeum brachyantherum and H. californicum (Triticeae: Poaceae) conspecific?

1989 ◽  
Vol 67 (1) ◽  
pp. 46-52 ◽  
Author(s):  
Bernard R. Baum ◽  
L. Grant Bailey
Keyword(s):  
Cross Validation ◽  
Bootstrap Method ◽  
Linear Classification ◽  
Separate Species ◽  
Morphometric Characters ◽  
Morphometric Analyses ◽  
High Degree ◽  
Range Of Variation ◽  
Classification Function ◽  
The Bootstrap Method

Justifications for recognizing H. brachyantherum Nevski and H. californicum Covas as separate species are provided from multivariate morphometric analyses and from lodicule and epiblast characters. Although the range of variation of the latter species is included in the range of the former for most morphometric characters, the two are distinct when all of the characters are in multivariate space. Furthermore, H. brachyantherum is allotetraploid (2n = 4X = 28) and H. californicum is diploid (2n = 2X = 14) as previously reported. Identification to species can be done with a high degree of accuracy by means of the linear classification function coefficients, which after cross validation using the bootstrap method, has been found to be reliable, by the lodicules and epiblasts, or more conclusively by the chromosome number.

scholarly journals Uncertainty and the ranking of economics journals

2020 ◽  
Vol 125 (3) ◽  
pp. 2545-2560
Author(s):  
Johan Lyhagen ◽  
Per Ahlgren
Keyword(s):  
Invariant Measure ◽  
Confidence Intervals ◽  
Bootstrap Method ◽  
Point Of View ◽  
Uncertainty Measure ◽  
Invariant Method ◽  
Bootstrap Approach ◽  
Economics Journals ◽  
High Degree ◽  
The Bootstrap Method

AbstractJournal rankings often show significant changes compared to previous rankings. This gives rise to the question of how well estimated the rank of a journal is. In this contribution, we consider uncertainty in a ranking of economics journals. We use the invariant method of Pinski and Narin to rank the journals. We propose an uncertainty measure, which is based on a bootstrap approach. The measure is the average absolute change in rank, which we see as a reasonable uncertainty measure regarding rankings. We further calculate, based on the bootstrap method, 95% confidence interval for the observed values of the invariant method. We show that ranks of the highest, as well as the lowest, ranked journals are well estimated, while there is a high degree of uncertainty regarding the rank of many mid-ranked journals. The distribution of the underlying measure is useful for identifying groups of journals that are more or less of the same quality (from the point of view of the invariant measure). The journal with the highest observed value of the invariant measure, Journal of Political Economy, has the best performance and constitutes a singleton, whereas Quarterly Journal of Economics and Econometrica form the next group (there is a slight overlap between the two with respect to confidence intervals). The journals ranked between about 190–230 form another group in which there are no major quality differences between the journals, as the confidence intervals are overlapping.

scholarly journals Statistical Estimates of the Pulsar Glitch Activity

Universe ◽  
2021 ◽  
Vol 7 (1) ◽  
pp. 8
Author(s):  
Alessandro Montoli ◽  
Marco Antonelli ◽  
Brynmor Haskell ◽  
Pierre Pizzochero
Keyword(s):  
Linear Regression ◽  
Upper Bound ◽  
Bootstrap Method ◽  
Waiting Times ◽  
Statistical Estimates ◽  
Equal Variance ◽  
Linear Fit ◽  
The Moment ◽  
The Bootstrap Method

A common way to calculate the glitch activity of a pulsar is an ordinary linear regression of the observed cumulative glitch history. This method however is likely to underestimate the errors on the activity, as it implicitly assumes a (long-term) linear dependence between glitch sizes and waiting times, as well as equal variance, i.e., homoscedasticity, in the fit residuals, both assumptions that are not well justified from pulsar data. In this paper, we review the extrapolation of the glitch activity parameter and explore two alternatives: the relaxation of the homoscedasticity hypothesis in the linear fit and the use of the bootstrap technique. We find a larger uncertainty in the activity with respect to that obtained by ordinary linear regression, especially for those objects in which it can be significantly affected by a single glitch. We discuss how this affects the theoretical upper bound on the moment of inertia associated with the region of a neutron star containing the superfluid reservoir of angular momentum released in a stationary sequence of glitches. We find that this upper bound is less tight if one considers the uncertainty on the activity estimated with the bootstrap method and allows for models in which the superfluid reservoir is entirely in the crust.

The Bootstrap-Method: Discussion and Proposal for Improvement / Das bootstrap-Verfahren: Diskussion und Verbesserungsvorschlag

1998 ◽  
Vol 217 (1) ◽  
Author(s):  
Hans Schneeberger
Keyword(s):  
Bootstrap Method ◽  
Law School ◽  
Mean Deviation ◽  
Alternative Method ◽  
Doubling Method ◽  
The Mean ◽  
The Bootstrap Method

SummaryWith Efron’s law-school example the bootstrap method is compared with an alternative method, called doubling. It is shown, that the mean deviation of the estimator is always smaller for the doubling method.

Taxonomic relationships of Nearctic small-footed bats of the Myotis leibii group (Chiroptera: Vespertilionidae)

1984 ◽  
Vol 62 (12) ◽  
pp. 2519-2526 ◽  
Author(s):  
C. G. van Zyll de Jong
Keyword(s):  
Canonical Variate Analysis ◽  
Canonical Variate ◽  
Separate Species ◽  
Taxonomic Relationships ◽  
Morphometric Analyses ◽  
Cranial Measurements ◽  
Variate Analysis ◽  
Myotis Leibii

Crania and bacula of five taxa of small-footed bats of the leibii group, comprising two currently recognised species, Myotis californicus and M. leibii, were studied to elucidate their interrelationships. Canonical variate analysis of 14 cranial measurements shows the existence of three distinct nonoverlapping clusters corresponding to (i) M. californicus, (ii) M. I. ciliolabrum and M. I. melanorhinus, and (iii) M. I. leibii. The results of the morphometric analyses do not support the claim that M. I. leibii and M. I. melanorhinus intergrade in Oklahoma. The taxonomic interpretation of the results is that the western forms of M. leibii represent a separate species M. ciliolabrum (Mcrriam). The bacula of the taxa studied lack distinctive characters that would allow one to discriminate between the species of the leibii group.

Application of the bootstrap method to quantify uncertainty in seismic hazard estimates

1992 ◽  
Vol 82 (1) ◽  
pp. 104-119
Author(s):  
Michéle Lamarre ◽  
Brent Townshend ◽  
Haresh C. Shah
Keyword(s):  
Confidence Interval ◽  
Seismic Hazard ◽  
Statistical Method ◽  
Bootstrap Method ◽  
Earthquake Magnitude ◽  
Earthquake Catalog ◽  
Uncertainty Measure ◽  
Attenuation Models ◽  
The Bootstrap Method

Abstract This paper describes a methodology to assess the uncertainty in seismic hazard estimates at particular sites. A variant of the bootstrap statistical method is used to combine the uncertainty due to earthquake catalog incompleteness, earthquake magnitude, and recurrence and attenuation models used. The uncertainty measure is provided in the form of a confidence interval. Comparisons of this method applied to various sites in California with previous studies are used to confirm the validity of the method.

Standard Error Estimation of 3PL IRT True Score Equating With an MCMC Method

2008 ◽  
Vol 33 (3) ◽  
pp. 257-278 ◽  
Author(s):  
Yuming Liu ◽  
E. Matthew Schulz ◽  
Lei Yu
Keyword(s):  
Bootstrap Method ◽  
Standard Errors ◽  
True Score ◽  
Mcmc Method ◽  
Test Form ◽  
True Score Equating ◽  
Standard Error Estimation ◽  
Equivalent Test ◽  
Mean Square Errors ◽  
The Bootstrap Method

A Markov chain Monte Carlo (MCMC) method and a bootstrap method were compared in the estimation of standard errors of item response theory (IRT) true score equating. Three test form relationships were examined: parallel, tau-equivalent, and congeneric. Data were simulated based on Reading Comprehension and Vocabulary tests of the Iowa Tests of Basic Skills®. For parallel and congeneric test forms within valid IRT true score ranges, the pattern and magnitude of standard errors of IRT true score equating estimated by the MCMC method were very close to those estimated by the bootstrap method. For tau-equivalent test forms, the pattern of standard errors estimated by the two methods was also similar. Bias and mean square errors of equating produced by the MCMC method were smaller than those produced by the bootstrap method; however, standard errors were larger. In educational testing, the MCMC method may be used as an additional or alternative procedure to the bootstrap method when evaluating the precision of equating results.

scholarly journals ACCURACY AND ERROR FACTORS OF SENSITOMETRIC CURVE USING THE BOOTSTRAP METHOD

1991 ◽  
Vol 47 (6) ◽  
pp. 811-817 ◽  
Author(s):  
AKIO OGURA ◽  
HIDEHARU NIIDA ◽  
KENICHI OGAWA ◽  
YOSHINORI KOMAI ◽  
HIDEHIKO TODOROKI ◽  
...  
Keyword(s):  
Bootstrap Method ◽  
The Bootstrap Method
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