Hypothesis testing and parameter estimation based onM-statistics ink samples with unequal variances

Summary Ink samples with unequal variances,M-tests for homogeneity ofk location parameters are proposed. The asymptoticχ ²-distributions of the test statistics and the robustness of the tests are investigated. NextM-estimators (ME’s) of parameters are discussed. Furthermore positive-part shrinkage versions (PSME’s) of theM-estimators for the location parameters are considered along with modified James-Stein estimation rule. In asymptotic distributional risks based on a special feasible loss, it is shown that the PSME’s dominate the ME’s, and preliminary test and shrinkageM-versions fork≧4.     

Factors in the Development of Trade Credit: Case Study of Provinces in China

Using Chinese province-level panel data for 2001-9, we investigate significant factors for the development of financial intermediation via trade credit in developing economies. First, we confirm that a competitive market environment, a well-functioning legal system, and greater bank loans for non-state-sector firms promote the development of trade credit in China. Conversely, corruption hinders its development. Second, we find that proper functioning of the legal system and bank lending to non-state-sector firms are highly likely to be the causes of the complex relationships between these determinants. Finally, we observe that an increase in the number of lawyers effectively improves the quality and function of the legal system, which, in turn, alleviates the harmful influence of corruption on trade credit development.     

Challenges to elderly safety in Safe Community movements in Japan

In Japan, with the longest life expectancy in the world over the last two decades, a great emphasis has been placed on the safety of the elderly, which has in turn influenced their well-being. Meantime, the concept of Safe Community (SC) has drawn more attention as one of the potential measures to sustain and improve the health conditions of the elderly. In hope of improving the effectiveness and efficiency of current efforts for elderly safety, the SC model is expected to provide features with which communities can make the better use of current limited resources. This article examines how the SC model makes a difference in these efforts by utilising existing programmes and how elderly safety can be promoted at the community level. Six communities working safety promotion based on the SC model were selected for the study. Although there are limitations to the information due to the insufficient experience in SC in Japan, it was found that two features make SC significant in promoting safety: (1) systematic evidence-based plan-do-check-action processes and (2) a framework of cross-sectoral collaboration. However, to examine and identify the effectiveness of SC on elderly health, further observation is required to develop strategies while accumulating longitudinal data.     

M-tests in multivariate models

Summary For testing homogeneity in multivariatek sample model, robust tests based onM-estimators are proposed and their asymptoticx ²-distributions are investigated. FurthermoreM-tests in multivariate regression models are discussed.     

A Note on the Term Structure of Implied Volatilities for the Yen/U.S. Dollar Currency Option

This paper tests the relationship between short dated and long dated implied volatilities obtained from Tokyo market currency option prices by employing three different volatility models: a mean reverting model, a GARCH model, and an EGARCH model. We document evidence that long dated average expected volatility is higher than that predicted by the term structure relationship during the dramatic appreciation of yen/dollar exchange in the early 1990's. This revised version was published online in August 2006 with corrections to the Cover Date.     

Comments

The marginal-products-of-labour (MPL) wage gap is studied in the early-reform Chinese economy, using the Olley-Pakes estimation technique to estimate the production function, based on micro data including different categories of labour. From this measurement of MPL-wage gaps and econometric analyses, several conclusions are drawn. First, the MPL-wage gap was anomalously large for managers in state-owned enterprises (SOEs) compared with other categories of labour. Second, the large MPL-wage gap of managers raised the average MPL-wage gap across various categories of labour, resulting in higher than the average wage MPL throughout the entire workforce, which is regarded as homogeneous. Third, the large MPL-wage gap, or, in other words, the under-employment of managers, occurred not only because the state still centrally employed and allocated labour to SOEs, but because the economy faced a labour-supply constraint of managers in early-reform China. This observation supports a modified version of the state labour-monopsony hypothesis.     

Semiparametric estimation in the optimal dividend barrier for the classical risk model

In the context of an insurance portfolio which provides dividend income for the insurance company’s shareholders, an important problem in risk theory is how the premium income will be paid to the shareholders as dividends according to a barrier strategy until the next claim occurs whenever the surplus attains the level of ‘barrier’. In this paper, we are concerned with the estimation of optimal dividend barrier, defined as the level of the barrier that maximizes the expected discounted dividends until ruin, under the widely used compound Poisson model as the aggregate claims process. We propose a semi-parametric statistical procedure for estimation of the optimal dividend barrier, which is critically needed in applications. We first construct a consistent estimator of the objective function that is complexly related to the expected discounted dividends and then the estimated optimal dividend barrier as the minimizer of the estimated objective function. In theory, we show that the constructed estimator of the optimal dividend barrier is statistically consistent. Numerical experiments by both simulated and real data analyses demonstrate that the proposed estimators work reasonably well with an appropriate size of samples.