China's exporters and importers: firms, products, and trade partners

This paper provides a detailed overview of China's participation in international trade using newly available data on the universe of globally engaged Chinese firms over the 2003-2005 period. We document the distribution of trade flows and product- and trade-partner intensity across both exporting and importing firms and study the relationship between firms' intensive and extensive margins of trade. We also compare trade patterns across firms of different organizational structure, distinguishing between domestic private firms, domestic state-owned firms, foreign-owned firms, and joint ventures. We explore the variation in foreign ownership across sectors, and find results consistent with recent theoretical and empirical work on the role of credit constraints and contractual imperfections in international trade and investment. Finally, we examine the rapid expansion of China's trade over the 2003-2005 period, and decompose it into its extensive and intensive margins. We also use monthly data and study the frequent churning and reallocation of trade flows across firms and across products and trade partners within firms.

MATS: Inference for potentially Singular and Heteroscedastic MANOVA

In many experiments in the life sciences, several endpoints are recorded per subject. The analysis of such multivariate data is usually based on MANOVA models assuming multivariate normality and covariance homogeneity. These assumptions, however, are often not met in practice. Furthermore, test statistics should be invariant under scale transformations of the data, since the endpoints may be measured on different scales. In the context of high-dimensional data, Srivastava and Kubokawa (2013) proposed such a test statistic for a specific one-way model, which, however, relies on the assumption of a common non-singular covariance matrix. We modify and extend this test statistic to factorial MANOVA designs, incorporating general heteroscedastic models. In particular, our only distributional assumption is the existence of the group-wise covariance matrices, which may even be singular. We base inference on quantiles of resampling distributions, and derive confidence regions and ellipsoids based on these quantiles. In a simulation study, we extensively analyze the behavior of these procedures. Finally, the methods are applied to a data set containing information on the 2016 presidential elections in the USA with unequal and singular empirical covariance matrices

Random Subsets of Structured Deterministic Frames have MANOVA Spectra

We draw a random subset of $k$ rows from a frame with $n$ rows (vectors) and $m$ columns (dimensions), where $k$ and $m$ are proportional to $n$. For a variety of important deterministic equiangular tight frames (ETFs) and tight non-ETF frames, we consider the distribution of singular values of the $k$-subset matrix. We observe that for large $n$ they can be precisely described by a known probability distribution -- Wachter's MANOVA spectral distribution, a phenomenon that was previously known only for two types of random frames. In terms of convergence to this limit, the $k$-subset matrix from all these frames is shown to be empirically indistinguishable from the classical MANOVA (Jacobi) random matrix ensemble. Thus empirically the MANOVA ensemble offers a universal description of the spectra of randomly selected $k$-subframes, even those taken from deterministic frames. The same universality phenomena is shown to hold for notable random frames as well. This description enables exact calculations of properties of solutions for systems of linear equations based on a random choice of $k$ frame vectors out of $n$ possible vectors, and has a variety of implications for erasure coding, compressed sensing, and sparse recovery. When the aspect ratio $m/n$ is small, the MANOVA spectrum tends to the well known Marcenko-Pastur distribution of the singular values of a Gaussian matrix, in agreement with previous work on highly redundant frames. Our results are empirical, but they are exhaustive, precise and fully reproducible

A Framework for Design-Time Testing of Service-Based Applications at BPEL Level

Software applications created on top of the service-oriented architecture (SOA) are increasingly popular but testing them remains a challenge. In this paper a framework named TASSA for testing the functional and non-functional behaviour of service-based applications is presented. The paper focuses on the concept of design time testing, the corresponding testing approach and architectural integration of the consisting TASSA tools. The individual TASSA tools with sample validation scenarios were already presented with a general view of their relation. This paper’s contribution is the structured testing approach, based on the integral use of the tools and their architectural integration. The framework is based on SOA principles and is composable depending on user requirements.The work reported in this paper was supported by a research project funded by the National Scientific Fund, Bulgarian Ministry of Education, Youth and Science, via agreement no. DOO2-182

Off the cliff and back? Credit conditions and international trade during the global financial crisis

Ministry of Education, Singapore under its Academic Research Funding Tier