Université de Fribourg

Nonparametric estimation of natural direct and indirect effects based on inverse probability weighting

Huber, Martin ; Yu-Chin, Hsu ; Tsung-Chih, Lai

In: Journal of Econometric Methods, 2019, vol. 8, no. 1, p. 1-20

Using a sequential conditional independence assumption, this paper discusses fully nonparametric estimation of natural direct and indirect causal effects in causal mediation analysis based on inverse probability weighting. We propose estimators of the average indirect effect of a binary treatment, which operates through intermediate variables (or mediators) on the causal path between the...

Université de Fribourg

Direct and indirect effects of training vouchers for the unemployed

Huber, Martin ; Lechner, Michael ; Strittmatter, Anthony

In: Journal of the Royal Statistical Society Series A, 2018, vol. 181, no. 2, p. 441-463

This paper evaluates the effects of awarding vouchers for vocational training on the employment outcomes of unemployed voucher recipients in Germany, as well as the potential mechanism through which they operate. This study assesses the direct effects of voucher assignment net of actual redemption, which may be driven by preference shaping and learning about possible human capital investments...

Université de Fribourg

Why do tougher caseworkers increase employment? : The role of programme assignment as a causal mechanism

Huber, Martin ; Lechner, Michael ; Mellace, Giovanni

In: Review of economics and statistics, 2017, vol. 99, no. 1, p. 180-183

Previous research found that less accommodating caseworkers are more success- ful in placing unemployed workers into employment. This paper explores the causal mechanisms behind this result using semiparametric mediation analysis. Analysing rich linked jobseeker-caseworker data for Switzerland, we find that the positive employment effects of less accommodating caseworkers are not driven by a ...

Université de Neuchâtel

Cleaner fish cause predators to reduce aggression toward bystanders at cleaning stations

Cheney, Karen L. ; Bshary, Redouan ; Grutter, Alexandra S.

In: Behavioral Ecology, 2008, vol. 19, no. 5, p. 1063-1067

Mutualisms, in which both participants gain a net benefit, are ubiquitous in all ecosystems, and the importance of understanding their broader ecological context has been demonstrated many times. Indirect effects of mutualisms may have important implications for surrounding ecosystems through changes in density, species composition, or behavior; however, the latter has been difficult to quantify....