We investigate conditions sufficient for identification of average treatment effects using instrumental variables. First we show that the existence of valid instruments is not sufficient to identify any meaningful average treatment effect. We then establish that the combination of an instrument and a condition on the relation between the instrument and the participation status is sufficient for identification of a local average treatment effect for those who can be induced to change their participation status by changing the value of the instrument. Finally we derive the probability limit of the standard IV estimator under these conditions. It is seen to be a weighted average of local average treatment effects.

Evolution and Rationality Some Recent Game-Theoretic Results. Identification and Estimation of Local Average Treatment Effects

We apply an understanding of what computers do to study how computerization alters job skill demands. We argue that computer capital (1) substitutes for workers in performing cognitive and manual tasks that can be accomplished by following explicit rules; and (2) complements workers in performing nonroutine problem-solving and complex communications tasks. Provided these tasks are imperfect substitutes, our model implies measurable changes in the composition of job tasks, which we explore using representative data on task input for 1960 to 1998. We find that within industries, occupations and education groups, computerization is associated with reduced labor input of routine manual and routine cognitive tasks and increased labor input of nonroutine cognitive tasks. Translating task shifts into education demand, the model can explain sixty percent of the estimated relative demand shift favoring college labor during 1970 to 1998. Task changes within nominally identical occupations account for almost half of this impact.

/pdf/the-skill-content-of-recent-technological-change-an-120y2lva5p.pdf

The Skill Content of Recent Technological Change: An Empirical Exploration

This paper shows that the United Kingdom since 1975 has exhibited a pattern of job polarization with rises in employment shares in the highest- and lowest-wage occupations. This is not entirely consistent with the idea of skill-biased technical change as a hypothesis about the impact of technology on the labor market. We argue that the “routinization” hypothesis recently proposed by Autor, Levy, and Murnane (2003) is a better explanation of job polarization, though other factors may also be important. We show that job polarization can explain one-third of the rise in the log(50/10) wage differential and one-half of the rise in the log(90/50).

/pdf/lousy-and-lovely-jobs-the-rising-polarization-of-work-in-2sso2du43s.pdf

Lousy and Lovely Jobs: The Rising Polarization of Work in Britain

Empirical work has been limited in its ability to directly study whether skill requirements in the workplace have been rising and whether these changes have been related to technological change. This article answers these questions using a unique data set from West Germany that enabled me to look at how skill requirements have changed within occupations. I show that occupations require more complex skills today than in 1979 and that the changes in skill requirements have been most pronounced in rapidly computerizing occupations. Changes in occupational content account for about 36% of the recent educational upgrading in employment.

https://www.jstor.org/stable/10.1086/499972

Technical Change, Job Tasks, and Rising Educational Demands: Looking outside the Wage Structure

This article studies how portable skills accumulated in the labor market are. Using rich data on tasks performed in occupations, we propose the concept of task‐specific human capital to measure empirically the transferability of skills across occupations. Our results on occupational mobility and wages show that labor market skills are more portable than previously considered. We find that individuals move to occupations with similar task requirements and that the distance of moves declines with experience. We also show that task‐specific human capital is an important source of individual wage growth, accounting for up to 52% of overall wage growth.

/pdf/how-general-is-human-capital-a-task-based-approach-2832ya7oq0.pdf

How General Is Human Capital? A Task-Based Approach

Unter dem Stichwort "Patchwork-Biografien" wird die Tatsache, dass ein groser Teil der abhangig Beschaftigten ihren erlernten Beruf nicht mehr ausuben, in jungster Zeit viel diskutiert. Diese Studie liefert einen empirischen Beitrag zur Anatomie der Berufswechsel fur westdeutsche Manner auf Basis der BIBB/IABDaten 1998/1999. Als Grundlage fur die empirische Analyse wird ein theoretisches Modell der Wahl zwischen horizontal differenzierten Berufen entwickelt. Die wichtigsten Ergebnisse sind: Ex post beobachtete Berufswechsel hangen negativ vom Durchschnittslohn im Ausbildungsberuf und positiv vom Durchschnittslohn im Erwerbsberuf ab. Der deskriptiv beobachtete durchschnittliche Entlohnungseffekt eines Berufswechsels ist signifikant positiv, verstarkt sich noch, wenn fur den Ausbildungsberuf kontrolliert wird, und ist demgegenuber signifikant negativ, wenn fur den Erwerbsberuf kontrolliert wird. Der geschatzte kausale durchschnittliche Entlohnungseffekt ist positiv. Die Ergebnisse sind insgesamt damit konsistent, dass Berufswechsel vor allem damit zusammenhangen, dass Beschaftigte im neuen Erwerbsberuf grosere Verdienst- und Karrierechancen wahrnehmen konnen.

https://ftp.zew.de/pub/zew-docs/dp/dp0405.pdf

Die Anatomie des Berufswechsels : eine empirische Bestandsaufnahme auf Basis der BIBB/IAB-Daten 1998/1999

The present analysis investigates skill requirements in the workplace, measured directly by the task-composition of occupations. It shows that the task composition of occupations has shifted toward analytical and interactive activities and away from manual and cognitive routine activities in West Germany between 1979 and 1999. These withinoccupational task changes account for around 50 percent of the educational upgrading in recent decades. The analysis shows additionally that computer technology is complementary to workers in executing analytical and interactive activities, whereas it substitutes for workers in performing manual and cognitive routine tasks. This relationship exists within occupations, within occupation-education groups and within occupation-age groups.

/pdf/are-skill-requirements-in-the-workplace-rising-stylized-1f9uqdazfy.pdf

Are Skill Requirements in the Workplace Rising? Stylized Facts and Evidence on Skill-Biased Technological Change

Based on a large data set containing information on occupations between 1979 and 1999, this study explores the "black box" surrounding the skill-biased technological change hypothesis by analyzing the mechanisms that induce information technologies to be complementary to employees with higher skill levels. Using direct, multidimensional measures of occupational skill requirements, the analysis shows that IT capital substitutes repetitive manual and repetitive cognitive skills, whereas it complements analytical and interactive skills. These changes in the within occupational task mix result in an increased deployment of employees with high levels of education who have comparative advantages in performing non-repetitive cognitive tasks.

/pdf/it-capital-job-content-and-educational-attainment-556r5anmay.pdf

IT Capital, Job Content and Educational Attainment

This paper aims at providing business survey analysts with simple econometric tools to quantify qualitative survey data. We extend the traditional and commonly applied method proposed by Carlson and Parkin (1975) to capture observable survey respondent heterogeneity. We also discuss specification tests. The empirical analysis is based on business survey data taken from the ZEW's 'Service Sector Business Survey', a quarterly business survey in the German business-related service sector carried out since 1994.

/pdf/quantification-of-qualitative-data-using-ordered-probit-278ub5kq12.pdf

Quantification of Qualitative Data Using Ordered Probit Models with an Application to a Business Survey in the German Service Sector

This paper studies the effect of managerial ownership on performance and the determinants of managerial ownership for small and medium–sized private companies. We use a panel of around 1300 firms in the German business–related service sector for the years 1997–2000. Managerial ownership up to around 80 per cent has a positive impact on firm performance (incentive effect), for higher shares the effect becomes negative (entrenchment effect). Moreover, risk–aversion of managers and signalling of firm quality leads to a non–linear relationship between managerial ownership and the risk exposure of a firm. The determinants of performance and ownership are estimated simultaneously.

/pdf/managerial-ownership-and-firm-performance-in-german-small-2cvg46muz5.pdf

Alexandra Spitz

Papers

Die Anatomie des Berufswechsels : eine empirische Bestandsaufnahme auf Basis der BIBB/IAB-Daten 1998/1999

Are Skill Requirements in the Workplace Rising? Stylized Facts and Evidence on Skill-Biased Technological Change

IT Capital, Job Content and Educational Attainment

Quantification of Qualitative Data Using Ordered Probit Models with an Application to a Business Survey in the German Service Sector

Managerial ownership and firm performance in German small and medium-sized enterprises