-
作者：Sherman, M
作者单位：Texas A&M University System; Texas A&M University College Station
-
作者：Eide, AL; Omre, H; Ursin, B
作者单位：Norwegian University of Science & Technology (NTNU); Norwegian University of Science & Technology (NTNU)
摘要：Offshore petroleum reservoirs are usually explored by acquisition of vast amounts of seismic reflection data and observations along a small number of wells drilled through the reservoirs. The seismic data a-re indirect measurements of reservoir characteristics and have good spatial coverage but low precision. The A ell observations are sparse but precise. Information from these sources of data are integrated to characterize the reservoir variables of interest-reservoir porosity in the current ...
-
作者：Liang, F
作者单位：National University of Singapore
摘要：This article describes a new Monte Carlo algorithm, dynamically weighted importance sampling (DWIS), for simulation and optimization. In DWIS, the state of the Markov chain is augmented to a population. At each iteration, the population is subject to two move steps, dynamic weighting and population control. These steps ensure that DWIS can move across energy barriers like dynamic weighting, but with the weights well controlled and with a finite expectation. The estimates can converge much fast...
-
作者：Kanaan, MN; Farrington, CP
作者单位：Open University - UK
摘要：Whether the protection afforded by a vaccine wanes over time and if so, by how much, are important public health questions with implications for mass immunization programs. However, the measurement of such effects is fraught with difficulties. Generally, clinical trials are too short to provide evidence on waning effects. Thus it is necessary to rely on epidemiologic data, which are subject to ascertainment bias. Furthermore, standard epidemiologic, measures, such as hazard ratios, may not acc...
-
作者：Newman, KB; Rice, J
作者单位：University of Idaho; University of California System; University of California Berkeley
摘要：To study the factors associated with the freshwater mortality of outmigrating chinook salmon, releases of tagged juvenile salmon were made at multiple locations in the Sacramento River each spring between the years 1979 and 1995. A midwater trawl located downstream of the release sites caught salmon soon after release and, 1 to 4 years later, samples taken from the catches of marine fisheries recovered other tagged fish. An extended quasi-likelihood model was fit to both the freshwater and the...
-
作者：Shen, XT; Huang, HC; Cressie, N
作者单位：University System of Ohio; Ohio State University
摘要：Nonparametric hypothesis testing for a spatial signal can involve a large number of hypotheses. For instance,, two satellite images of the same scene, taken before and after an event, could be used to test a hypothesis that the event has no environmental impact. This is equivalent to testing that the mean difference of after-before is zero at each of the (typically thousands of) pixels that make up the scene. In such a situation, conventional testing procedures that control the overall type I ...
-
作者：Christensen, WF; Amemiya, Y
作者单位：Southern Methodist University; Iowa State University
摘要：Multivariate spatial or geo-referenced data arise naturally in such disciplines as ecology, agriculture, geology, and atmospheric sciences. In practice, interest often lies in modeling underlying structure and representing interrelationships in terms of a smaller number of variables. For such situations, statistical analysis using a latent variable model is proposed. We present a general model that incorporates spatial correlation and potential lagged or shifted dependencies and that can repre...
-
作者：Barsky, R; Bound, J; Charles, KK; Lupton, JP
作者单位：University of Michigan System; University of Michigan; Federal Reserve System - USA; Federal Reserve System Board of Governors
摘要：Many applications involve a decomposition of the mean intergroup difference in a given variable into the portion attributable to differences in the distribution of one or more explanatory variables and that due to differences in the conditional expectation function. This article notes two interrelated reasons why the Blinder-Oaxaca (B-O) method-the approach most commonly used in the literature-may yield misleading results. We suggest a natural solution that both provides a more reliable answer...
-
作者：Dominici, F; Daniels, M; Zeger, SL; Samet, JM
作者单位：Johns Hopkins University; Johns Hopkins Bloomberg School of Public Health; Iowa State University; Johns Hopkins University
摘要：We analyzed a national data base of air pollution and mortality for the 88 largest U.S. cities for the period 1987-1994, to estimate relative rates of mortality associated with airborne particulate matter smaller than 10 microns (PM,,) and the form of the relationship between PM10 concentration and mortality. To estimate city-specific relative rates of mortality associated with PM,,, we built log-linear models that included nonparametric adjustments for weather variables and longer term trends...
-
作者：Gneiting, T
作者单位：University of Washington; University of Washington Seattle
摘要：Geostatistical approaches to spatiotemporal prediction in environmental science, climatology, meteorology. and related fields rely on appropriate covariance models. This article proposes general classes of nonseparable, stationary covariance functions for spatiotemporal random processes, The constructions are directly in the space-time domain and do not depend on closed-form Fourier inversions. The model parameters can be associated with the data's spatial and temporal structures, respectively...
