4,337 research outputs found
False discovery and false nondiscovery rates in single-step multiple testing procedures
Results on the false discovery rate (FDR) and the false nondiscovery rate
(FNR) are developed for single-step multiple testing procedures. In addition to
verifying desirable properties of FDR and FNR as measures of error rates, these
results extend previously known results, providing further insights,
particularly under dependence, into the notions of FDR and FNR and related
measures. First, considering fixed configurations of true and false null
hypotheses, inequalities are obtained to explain how an FDR- or FNR-controlling
single-step procedure, such as a Bonferroni or \u{S}id\'{a}k procedure, can
potentially be improved. Two families of procedures are then constructed, one
that modifies the FDR-controlling and the other that modifies the
FNR-controlling \u{S}id\'{a}k procedure. These are proved to control FDR or FNR
under independence less conservatively than the corresponding families that
modify the FDR- or FNR-controlling Bonferroni procedure. Results of numerical
investigations of the performance of the modified \u{S}id\'{a}k FDR procedure
over its competitors are presented. Second, considering a mixture model where
different configurations of true and false null hypotheses are assumed to have
certain probabilities, results are also derived that extend some of Storey's
work to the dependence case.Comment: Published at http://dx.doi.org/10.1214/009053605000000778 in the
Annals of Statistics (http://www.imstat.org/aos/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Selection Bias Correction and Effect Size Estimation under Dependence
We consider large-scale studies in which it is of interest to test a very
large number of hypotheses, and then to estimate the effect sizes corresponding
to the rejected hypotheses. For instance, this setting arises in the analysis
of gene expression or DNA sequencing data. However, naive estimates of the
effect sizes suffer from selection bias, i.e., some of the largest naive
estimates are large due to chance alone. Many authors have proposed methods to
reduce the effects of selection bias under the assumption that the naive
estimates of the effect sizes are independent. Unfortunately, when the effect
size estimates are dependent, these existing techniques can have very poor
performance, and in practice there will often be dependence. We propose an
estimator that adjusts for selection bias under a recently-proposed frequentist
framework, without the independence assumption. We study some properties of the
proposed estimator, and illustrate that it outperforms past proposals in a
simulation study and on two gene expression data sets.Comment: 21 pages, 2 figure
Gap bootstrap methods for massive data sets with an application to transportation engineering
In this paper we describe two bootstrap methods for massive data sets. Naive
applications of common resampling methodology are often impractical for massive
data sets due to computational burden and due to complex patterns of
inhomogeneity. In contrast, the proposed methods exploit certain structural
properties of a large class of massive data sets to break up the original
problem into a set of simpler subproblems, solve each subproblem separately
where the data exhibit approximate uniformity and where computational
complexity can be reduced to a manageable level, and then combine the results
through certain analytical considerations. The validity of the proposed methods
is proved and their finite sample properties are studied through a moderately
large simulation study. The methodology is illustrated with a real data example
from Transportation Engineering, which motivated the development of the
proposed methods.Comment: Published in at http://dx.doi.org/10.1214/12-AOAS587 the Annals of
Applied Statistics (http://www.imstat.org/aoas/) by the Institute of
Mathematical Statistics (http://www.imstat.org
Structural Change in Covariance and Exchange Rate Pass-Through: The Case of Canada
The authors address empirically the implications of structural breaks in the variance-covariance matrix of inflation and import prices for changes in pass-through. They define pass-through within a correlated vector autoregression (VAR) framework as the response of domestic inflation to an impulse in import price inflation. This approach allows them to examine changes in both the amount and the duration of pass-through.Econometric and statistical methods
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