Does studying abroad enhance employability?

Over 200,000 European students study abroad under the Erasmus programme. It appears that studying abroad may impart skills which are helpful for professional careers after graduation. Approximately, 54% of European students report that participation in the Erasmus exchange programme helped them to obtain a first job; however, interestingly, those from Central and Eastern European countries report it much more often—in 73% of cases. The aim of this paper is to find out whether studying abroad enhances the employability of higher education graduates in Poland. Using the propensity score matching method and data from a nationwide tracer survey of Polish graduates, we find that Polish students who completed at least one semester of their studies abroad do not benefit in terms of a higher employment rate after graduation.     

Density estimation in the uniform deconvolution model

We consider the problem of estimating a probability density function based on data that are corrupted by noise from a uniform distribution. The (nonparametric) maximum likelihood estimator for the corresponding distribution function is well defined. For the density function this is not the case. We study two nonparametric estimators for this density. The first is a type of kernel density estimate based on the empirical distribution function of the observable data. The second is a kernel density estimate based on the MLE of the distribution function of the unobservable (uncorrupted) data.     

对小地区失业统计差额比的推定

本文对韩国国内行政区域如市郡区等小地区的失业统计共同差额比进行推定的方法有联合推定量,Woolf推定量和Mantel-Haenszel推定量等。对这个推定量的可信度是通过偏差和平均平方误差的概念来进行比较的。从对京畿地区经济活动人口调查情况看,这个地区内的24个市郡单位行政自治地区的男、女失业率差额比的偏差及平均平方误差是通过本次研究提出的推定程序来推定的。这些推定数的稳定性和效率性可以通过相对偏差和相对平均误差平方根来评价。Woolf推定量或Mantel-Haenszel推定量比联合推定量更为稳定,从其效率性来看三者很相似。     

On Testing for the Nullity of Some Skewness Coefficients

Three tests for the skewness of an unknown distribution are derived for iid data. They are based on suitable normalization of estimators of some usual skewness coefficients. Their asymptotic null distributions are derived. The tests are next shown to be consistent and their power under some sequences of local alternatives is investigated. Their finite sample properties are also studied through a simulation experiment, and compared to those of the √ b ₂-test.     

Model-based control charts in phase 1 statistical process control

In this paper, a general method of constructing control charts for preliminary analysis of individual observations is presented, which is based on recursive score residuals. A simulation study shows that certain implementations of these charts are highly effective in detecting assignable causes.     

Are Venture Capitalists a Catalyst for Innovation?

In this paper we test two hypotheses concerning the presence of innovation in venture capital investments and the growth of innovative venture backed firms. To examine these hypotheses we considered sample of 37 Italian venture backed firms that went public on the Italian Stock Exchange between 1995 and 2004 and by a statistical matching procedure we picked 37 twin firms among the non‐venture backed IPOs for the same period. Our evidence shows that innovation is an important factor during the selection phase but once the investment is made, the company does not promote continued innovation and concentrates all efforts to improve other economic and managerial aspects.     

On efficiency of the ratio estimator

Summary The exact mean square error for the ratio estimator of a finite population total based on simple random sampling without replacement is shown to have an expected value less than that of the variance of the ratio estimator based on Midzuno’s scheme, under a usual super-population model.     

Locally minimum variance unbiased estimator in a discontinuous density function

The exact forms of the locally minimum variance unbiased estimators and their variances are given in the case of a discontinuous density function.