Are the self-employed really jacks-of-all-trades? Testing the assumptions and implications of Lazear's theory of entrepreneurship with German data

Using a large representative German data set and various concepts of self-employment, this paper tests the 'jack-of-all-trades' view of entrepreneurship by Lazear (AER 2004). Consistent with its theoretical assumptions we find that self-employed individuals perform more tasks and that their work requires more skills than that of paid employees. In contrast to Lazear's assumptions, however, self-employed individuals do not just need more basic but also more expert skills than employees. Our results also provide only very limited support for the idea that human capital investment patterns differ between those who become self-employed and those ending up in paid employment. -- Unter Verwendung eines großen, repräsentativen Datensatzes für Deutschland und verschiedener Abgrenzungen der Selbständigkeit überprüft diese Arbeit die 'jack-of-all-trades'-Sicht des Unternehmertums von Lazear (AER 2004). In Übereinstimmung mit ihren theoretischen Annahmen finden wir, dass Selbständige mehr verschiedene Tätigkeiten ausüben und Kenntnisse aus mehr verschiedenen Gebieten benötigen als nicht-selbständige Arbeitnehmer. Im Gegensatz zu Lazear's Annahmen benötigen Selbständige allerdings nicht nur mehr Grundkenntnisse sondern auch mehr Fachkenntnisse als Nicht-Selbständige. Unsere Ergebnisse liefern zudem nur wenig Unterstützung für die Behauptung, dass sich die Muster der Humankapitalaneignung zwischen Selbstständigen und abhängig beschäftigten Arbeitnehmern sichtbar unterscheiden.entrepreneurship,self-employed,Germany

Are the self-employed really jacks-of-all-trades? Testing the assumptions and implications of Lazear's theory of entrepreneurship with German data

Using a large representative German data set and various concepts of self-employment, this paper tests the jack-of-all-trades view of entrepreneurship by Lazear (AER 2004). Consistent with its theoretical assumptions we find that self-employed individuals perform more tasks and that their work requires more skills than that of paid employees. In contrast to Lazear's assumptions, however, self-employed individuals do not just need more basic but also more expert skills than employees. Our results also provide only very limited support for the idea that human capital investment patterns differ between those who become self-employed and those ending up in paid employment. -- Unter Verwendung eines großen, repräsentativen Datensatzes für Deutschland und verschiedener Abgrenzungen der Selbständigkeit überprüft diese Arbeit die jack-of-all-trades-Sicht des Unternehmertums von Lazear (AER 2004). In Übereinstimmung mit ihren theoretischen Annahmen finden wir, dass Selbständige mehr verschiedene Tätigkeiten ausüben und Kenntnisse aus mehr verschiedenen Gebieten benötigen als nicht-selbständige Arbeitnehmer. Im Gegensatz zu Lazear's Annahmen benötigen Selbständige allerdings nicht nur mehr Grundkenntnisse sondern auch mehr Fachkenntnisse als Nicht-Selbständige. Unsere Ergebnisse liefern zudem nur wenig Unterstützung für die Behauptung, dass sich die Muster der Humankapitalaneignung zwischen Selbstständigen und abhängig beschäftigten Arbeitnehmern sichtbar unterscheiden.entrepreneurship,self-employed,Germany

Changes in union membership over time : a panel analysis for West Germany

Despite the apparent stability of the wage bargaining institutions in West Germany, aggregate union membership has been declining dramatically since the early 90's. However, aggregate gross membership numbers do not distinguish by employment status and it is impossible to disaggregate these sufficiently. This paper uses four waves of the German Socioeconomic Panel in 1985, 1989, 1993, and 1998 to perform a panel analysis of net union membership among employees. We estimate a correlated random effects probit model suggested in Chamberlain (1984) to take proper account of individual specfic effects. Our results suggest that at the individual level the propensity to be a union member has not changed considerably over time. Thus, the aggregate decline in membership is due to composition effects. We also use the estimates to predict net union density at the industry level based on the IAB employment subsample for the time period 1985 to 1997. JEL - Klassifikation: J

Cryogenic Q-factor measurement of optical substrates for optimization of gravitational wave detectors

Future generations of gravitational wave interferometers are likely to be operated at cryogenic temperatures because one of the sensitivity limiting factors of the present generation is the thermal noise of end mirrors and beam splitters that occurs in the optical substrates as well as in the dielectric coatings. A possible method for minimizing thermal noise is cooling to cryogenic temperatures, maximizing the mechanical quality factor Q, and maximizing the eigenfrequencies of the substrate. We present experimental details of a new cryogenic apparatus that is suitable for the measurement of the temperature-dependent Q-factor of reflective, transmissive as well as nano-structured grating optics down to 5 K. In particular, the SQUID-based and the optical interferometric approaches to the measurement of the amplitude of vibrating test bodies are compared and the method of ring-down recording is described

Variability of gully erosion in a small catchment in South-west Spain

Research on gully erosion is carried out as part of an investigation on erosional and hydrological processes in a small catchment in Extremadura, Spain. The amount of gully erosion is estimated by repeated monitonng of transverse sections since summer 1990. Data obtained so far indicate high spatial and temporal variability. High amounts of erosion are related to a channel section with active headcut retreat, whereas net accumulation occurs where the gully is already deep and wide. Present erosion, apart from headcut retreat, is related to lateral undercutting of the channel bank and bank collapsing. Temporal variability is related with rainfall characteristics and discharge production in the channel. Important sediment losses are produced by highly intensive storms. The most important gully process in the area is shown to be related with the erosive force of flowing surface waters. Furthermore it is discussed whether present active erosion is related to abandonment of cereal cultivation in parts of the catchment about 30 years ago. It is thought that reduced soil erosion on hillslopes due to the change in landuse, and hence lower sediment supply to the channel in the last decades increased gullying

Quantum engineering of squeezed states for quantum communication and metrology

We report the experimental realization of squeezed quantum states of light, tailored for new applications in quantum communication and metrology. Squeezed states in a broad Fourier frequency band down to 1 Hz has been observed for the first time. Nonclassical properties of light in such a low frequency band is required for high efficiency quantum information storage in electromagnetically induced transparency (EIT) media. The states observed also cover the frequency band of ultra-high precision laser interferometers for gravitational wave detection and can be used to reach the regime of quantum non-demolition interferometry. And furthermore, they cover the frequencies of motions of heavily macroscopic objects and might therefore support the attempts to observe entanglement in our macroscopic world.Comment: 12 pages, 3 figure