Business establishment microdata typically are required to satisfy agency-specified edit rules, such as balance equations and linear inequalities. Inevitably some establishments' reported data violate the edit rules. Statistical agencies correct faulty values using a process known as edit-imputation. Business establishment data also must be heavily redacted before being shared with the public; indeed, confidentiality concerns lead many agencies not to share establishment microdata as unrestricted access files. When microdata must be heavily redacted, one approach is to create synthetic data, as done in the U.S. Longitudinal Business Database and the German IAB Establishment Panel. This article presents the first implementation of a fully integrated approach to edit-imputation and data synthesis. We illustrate the approach on data from the U.S. Census of Manufactures and present a variety of evaluations of the utility of the synthetic data. The paper also presents assessments of disclosure risks for several intruder attacks. We find that the synthetic data preserve important distributional features from the post-editing confidential microdata, and have low risks for the various attacks. 相似文献
This paper discusses a novel strategy for simulating rare events and an associated Monte Carlo estimation of tail probabilities.
Our method uses a system of interacting particles and exploits a Feynman-Kac representation of that system to analyze their
fluctuations. Our precise analysis of the variance of a standard multilevel splitting algorithm reveals an opportunity for
improvement. This leads to a novel method that relies on adaptive levels and produces, in the limit of an idealized version
of the algorithm, estimates with optimal variance. The motivation for this theoretical work comes from problems occurring
in watermarking and fingerprinting of digital contents, which represents a new field of applications of rare event simulation
techniques. Some numerical results show performance close to the idealized version of our technique for these practical applications. 相似文献
This article explores the obligations of presence behind work-related mobility for academics in internationalizing higher education systems. By further developing John Urry’s concept of ‘meetingness’, the article reveals how academics depend on corporeal and virtual mobility to create and maintain a networked professional life outside their own institution, which is crucial in the context of changing work conditions. Our insights are drawn from original qualitative research (42 interviews) in a Flemish and Danish context. The data reveal obligations of presence associated with an interrelated mix of functionality, and the construction of dense and sparse social networks that together support career success and work at the frontiers of academic knowledge. Despite the now well-recognized costs of corporeal mobility, obligations of presence result in virtual and corporeal mobility coexisting, rather than the former substituting for the latter. Virtual mobility is mainly used when conflicting obligations of presence exist, and as a means of sustaining networks over time given the processual nature of meetingness, rather than as a means to reduce levels of corporeal mobility. 相似文献
We present influence diagnostics for linear measurement error models with stochastic linear restrictions using the corrected likelihood of Nakamura in 1990. The case deletion and mean shift outlier models are developed to identify outlying and influential observations. We derive a corrected score test statistic for outlier detection based on mean shift outlier models. The analogs of Cook's distance and likelihood distance are proposed to determine influential observations based on case deletion models. A parametric bootstrap procedure is used to obtain empirical distributions of the test statistics and a simulation study has been used to evaluate the performance of the proposed estimators based on the mean squares error criterion and the score test statistic. Finally, a numerical example is given to illustrate the theoretical results. 相似文献
Lawns are considered monocultures and lesser contributors to sustainability than diverse nature but are still a dominating green area feature and an important cultural phenomenon in cities. Lawns have esthetical values, provide playground, are potential habitat for species, contribute to carbon sequestration and water infiltration, but also increase pesticides, fertilization, are monocultures and costly to manage at the same time. To evaluate the potential impact of lawns, whether positive or negative, it is of interest to estimate the total lawn cover in cities and its change over time. This is not a straightforward process, e.g., because many lawns are small and covered by trees. In this study we review the existing literature of lawn cover in cities and the different methodologies used for cover estimation. We found both pros and cons with NDVI and LiDAR data as well as manually interpreted aerial photos. The total cover of lawns in three case study cities was estimated to 22.5%. By extrapolating these percentages to all Swedish cities lawn cover was estimated to 2589 km2 (0.6% of the terrestrial surface). The approximated total municipal management cost of lawns in all Swedish cities was 910,000,000 USD/ year. During 50 years lawn area almost doubled in relative cover and 56% of them were continuously managed. Since lawns constitute large parts of the urban greenery and are costly to manage it is highly relevant to consider their social, ecological and cultural value compared to alternatives, e.g., meadows with less intensive management. 相似文献
For over 50 years (1958–2012) the American National Election Studies (ANES) survey has been measuring citizens’ evaluations of the trustworthiness of the “government in Washington”—an indicator that has been widely used to monitor the dynamics of political trust in the US over time. However, a critical assumption in using attitudinal constructs for longitudinal research is that the meaning-and-interpretation of such items should be comparable across groups of respondents at any one point in time and across samples over time. Using multigroup confirmatory factor analysis for ordered-categorical data, we test the measurement equivalence assumption with data collected by the ANES from 1964 to 2008. The results confirm that the ANES’ political trust scale has the same basic factorial structure over time. But for two key items, several threshold parameters were found to be different across time points, indicating that the meaning-and-interpretation of these questions, and especially the question about whether the government in Washington wastes money that people pay in taxes, varies significantly over time.
Urban Ecosystems - Private residential property occupies a major part of the urban land base, yet considerable potential remains for improving the ecological performance of private gardens and... 相似文献