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作者：Cai, T. T.; Li, H.; Ma, J.; Xia, Y.
作者单位：University of Pennsylvania; University of Pennsylvania; Fudan University
摘要：Micro-organisms such as bacteria form complex ecological community networks that can be greatly influenced by diet and other environmental factors. Differential analysis of microbial community structures aims to elucidate systematic changes during an adaptive response to changes in environment. In this paper, we propose a flexible Markov random field model for microbial network structure and introduce a hypothesis testing framework for detecting differences between networks, also known as diff...
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作者：Jiang, F.; Ma, Y.; Wei, Y.
作者单位：University of Hong Kong; Pennsylvania Commonwealth System of Higher Education (PCSHE); Pennsylvania State University; Pennsylvania State University - University Park; Columbia University
摘要：Rapid improvement in technology has made it relatively cheap to collect genetic data, however statistical analysis of existing data is still much cheaper. Thus, secondary analysis of single-nucleotide polymorphism, SNP, data, i.e., reanalysing existing data in an effort to extract more information, is an attractive and cost-effective alternative to collecting new data. We study the relationship between gene expression and SNPs through a combination of factor analysis and dimension reduction es...
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作者：Tank, A.; Fox, E. B.; Shojaie, A.
作者单位：University of Washington; University of Washington Seattle; University of Washington; University of Washington Seattle
摘要：Causal inference in multivariate time series is challenging because the sampling rate may not be as fast as the time scale of the causal interactions, so the observed series is a subsampled version of the desired series. Furthermore, series may be observed at different sampling rates, yielding mixed-frequency series. To determine instantaneous and lagged effects between series at the causal scale, we take a model-based approach that relies on structural vector autoregressive models. We present...
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作者：He, Xu
作者单位：Chinese Academy of Sciences; Academy of Mathematics & System Sciences, CAS
摘要：We propose a new method to construct maximin distance designs with arbitrary numbers of dimensions and points. The proposed designs hold interleaved-layer structures and are by far the best maximin distance designs in four or more dimensions. Applicable to distance measures with equal or unequal weights, our method is useful for emulating computer experiments when a relatively accurate a priori guess on variable importance is available.
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作者：Karmakar, B.; French, B.; Small, D. S.
作者单位：University of Pennsylvania; Radiation Effects Research Foundation - Japan
摘要：A sensitivity analysis for an observational study assesses how much bias, due to nonrandom assignment of treatment, would be necessary to change the conclusions of an analysis that assumes treatment assignment was effectively random. The evidence for a treatment effect can be strengthened if two different analyses, which could be affected by different types of biases, are both somewhat insensitive to bias. The finding from the observational study is then said to be replicated. Evidence factors...
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作者：Chen, S.; Haziza, D.; Leger, C.; Mashreghi, Z.
作者单位：University of Oklahoma System; University of Oklahoma Health Sciences Center; Universite de Montreal; University of Winnipeg
摘要：The most common way to treat item nonresponse in surveys is to replace a missing value by a plausible value constructed on the basis of fully observed variables. Treating the imputed values as if they were observed may lead to invalid inferences. Bootstrap variance estimators for various finite population parameters are obtained using two pseudo-population bootstrap schemes. We establish the asymptotic properties of the resulting bootstrap variance estimators for population totals and populati...
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作者：Basse, G. W.; Feller, A.; Toulis, P.
作者单位：University of California System; University of California Berkeley; University of California System; University of California Berkeley; University of Chicago
摘要：Many causal questions involve interactions between units, also known as interference, for example between individuals in households, students in schools, or firms in markets. In this paper we formalize the concept of a conditioning mechanism, which provides a framework for constructing valid and powerful randomization tests under general forms of interference. We describe our framework in the context of two-stage randomized designs and apply our approach to a randomized evaluation of an interv...
