with Sarah Necker

Submitted to American Economic Journal: Economic Policy

Sales of services to consumers provide fertile ground for collaborative tax evasion. Little is known about the phenomenon. We conduct a natural field experiment with 2,900 businesses in Germany. We take the role of consumers and vary if we request an invoice for the delivery of a service. We find that 56% of businesses approach consumers with the intention to evade. The fraction is zero in a restrictive market and 72% in a non-restrictive market. It increases when consumers signal their willingness to collude. Consumers can save 25% of the legal price on average if they agree to evade.


submitted to Journal of Human Resources

This paper studies how training vouchers increase the employment prospects of women with interrupted employment histories. Using the population of female job returners who receive a training voucher to participate in training courses and a randomly selected control group from German administrative data, I analyze the effectiveness of training on various labor market outcomes. The results suggest that the receipt of a training voucher translates into a higher employment probability and higher monthly earnings. I find a positive impact on the job quality, e.g. the probability to be full-time employed increases significantly. In contrast, the probability to be marginally employed decreases by 5 percentage points in the long-run. I count this as an indicator for employment stability. The investigation of effect heterogeneity reveals some interesting insights regarding the vocational degrees, and the different types of training courses. The effectiveness of vocational training increases with the provided human capital in the courses. Several robustness checks support a causal interpretation of the results and highlight the importance of vocational training for the very special sub-group of female job-returners.


with Anthony Strittmatter
Revise and resubmit at Journal of Econometric Methods

We study the identification of channels of policy reforms with multiple treatments and different types of selection for each treatment. We disentangle reform effects into policy effects, selection effects, and time effects under the assumption of conditional independence, common trends, and an additional exclusion restriction on the non-treated. Furthermore, we show the identification of direct- and indirect policy effects after imposing additional sequential conditional independence assumptions on mediating variables. We illustrate the approach using the German reform of the allocation system of vocational training for unemployed persons. The reform changed the allocation of training from a mandatory system to a voluntary voucher system. Simultaneously, the selection criteria for participants changed. Furthermore, the reform altered the composition of course types. We consider the course composition as a mediator of the policy reform. We show that the empirical evidence from previous studies reverses when considering the course composition. This has important implications for policy conclusions.

Industrial & Labor Relations Review, 2017, Vol. 70 (3). pp 767-812
with Bernd Fitzenberger, Thomas Kruppe, Marie Paul, Anthony Strittmatter

Participation in intensive training programs for the unemployed in Germany is allocated by awarding training vouchers. Using rich administrative data for all vouchers and actual program participation, the authors provide first estimates of the short-run and long-run employment and earnings effects of receiving a training voucher award based on a selection-on-observables assumption. The results imply that, after the award, voucher recipients experience long periods of lower labor market success compared to had they not received training vouchers. Small positive employment effects and no gains in earnings were observed four to seven years after the receipt of the voucher award. In addition, the findings suggest stronger positive effects both for all low-skilled individuals who were awarded and redeemed a voucher and for low-skilled and medium-skilled individuals who chose to take degree courses than for higher-skilled recipients.

Journal for Labour Market Research, 2016, Vol. 49 (4), pp 329–347
with Bernd Fitzenberger (Paper is in written in German)

This paper provides a summary and a critical assessment of the evaluation studies on sectoral minimum wages in Germany, which were commissioned by the Federal Ministry of Labour and Social Affairs (BMAS). The evaluation of sectoral minimum wages is an important and successful example for the move towards evidence-based economic policy. All evaluation studies share the difficulty to identify the employees in the sectors which were actually covered by the sector specific minimum wage. We provide a critical discussion of the identifying assumptions, of the implementation of the difference-in-differences estimator, and of the choice of control groups. We discuss some alternative methodological approaches. We think that it would have been useful to analyze further the heterogeneity of the effect estimates and the choice of appropriate control groups. Furthermore, it would have been useful to assess the likely bias of the estimated effects.

Journal for Labour Market Research, 2015, Vol. 48 (1), pp 41-56
with Thomas Kruppe

This paper analyzes how the policy style of local employment agencies is correlated with the award intensity of training vouchers for the unemployed - an important instrument of Active Labor Market Policy (ALMP) in Germany. We define the policy style of agencies on the basis of caseworkers’ and managers’ assessments regarding the voucher system and information on internal organization, cooperative and communicative behavior. We use unique survey data in combination with data on training voucher awards from the Federal Employment Agency. Our results suggest that cooperative behavior and communication have a positive influence on the intensity of training voucher awards after we control for regional and labor market characteristics.