Does the online collection of ego-centered network data reduce data quality? An experimental comparison

We analyze whether differences in kind and quality of ego-centered network data are related to whether the data are collected online or offline. We report the results of two studies. In the first study respondents could choose between filling out ego-centered data through a web questionnaire and being probed about their network in a personalized interview. The second study used a design in which respondents were allocated at random to either online or offline data collection. Our results show that the data quality suffers from the online data collection and the findings indicate that this is the consequence of the respondents answering “mechanically”. We conclude that network researchers should avoid to simply copy traditional network items into a web questionnaire. More research is needed about how new design elements specific for web questionnaires can motivate respondents to fill out network questions properly.     

Hiring older workers and employing older workers: German evidence

Using German establishment data, we examine the relationship between delayed compensation, training, and hiring of older workers. Both those establishments that delay compensation and those with greater human capital requirements are less likely to hire older workers. We demonstrate that the routinely used control for the age of existing workers is endogenous and that instrumenting provides stronger evidence for the role of delayed compensation. Specifically, delayed compensation is simultaneously a negative determinant of hiring older workers but a positive determinant of employing older workers and, thus, more clearly associated with “employing older workers but not hiring them.”     

Health and economic development—evidence from the introduction of public health care

This paper investigates the causal effect of improvements in health on economic development using a long panel of European countries. Identification is based on the particular timing of the introduction of public health care systems in different countries, which is the random outcome of a political process. We document that the introduction of public health care systems had a significant immediate effect on health dynamics proxied by infant mortality and crude death rates. The findings suggest that health improvements had a positive effect on growth in income per capita and aggregate income.     

Effect of neglected deterministic seasonality on unit root tests

Whenever deterministic seasonality is ignored, the distribution of the Dickey-Fuller test is shifted to the left, with lower dispersion at the same time. When accounting for serial correlation, the distortions become less predictable. A Monte Carlo study confirms that the (augmented) Dickey-Fuller test without seasonal dummies is oversized and has little power at the same time, due to the need of lag augmentation. The effect of neglecting seasonal deterministics on the KPSS test for stationarity depends on the way the long-run variance is estimated. This is a shorter version of a working paper containing additional experimental evidence and the proofs of the propositions. The working paper is available online under http://www.wiwi.uni-frankfurt.de/~deme/ends_urt.pdf.     

Burnout and Mental Health in Swiss Vocational Students: The Moderating Role of Physical Activity

Few studies have focused on burnout among vocational students. This study examined the association between burnout and mental health among 56 Swiss vocational students (29 males, 27 females, M = 18.1, SD = 1.2 years) and tested whether recommended levels of moderate‐to‐vigorous physical activity (MVPA) attenuate this relationship. Burnout was strongly associated with increased depressive symptoms and decreased levels of life satisfaction, mental toughness, and quality of sleep. Students above recommended levels of MVPA reported lower burnout and higher mental health. No significant moderator effects were observed. Symptoms of burnout were associated with increased mental health problems. Physical activity should be promoted to prevent burnout, because nearly half of the students did not meet MVPA recommendations.     

中国加入WTO的重点领域:农业及其补贴

以中国加入 WTO谈判为背景 ,结合中国的农业发展水平和农产品贸易状况以及WTO《农业协议》等有关协议 ,通过国际比较 ,分析了中国加入 WTO后对世界农业发展和农产品贸易可能产生的影响 ,并对与此有关的农业补贴问题和国有贸易公司改革问题进行了探讨。