We show how instrumental variable and matching estimators can be combined in order to identify a broader array of treatment effects. Instrumental variable (IV) estimators are known to estimate effects only for the compliers, representing a subset of the entire population. By combining IV with matching, we can estimate the treatment effects for the always- and never-takers as well. Since in many cases these groups are the (endogenous) outcome of some assignment process, such estimates also help in judging the implications of such a selection process. In our application to the effects of participation in active labour market programmes in Switzerland, we find large and lasting positive employment effects for the compliers, whereas the effects for the always- and never-participants are small. In addition, the compliers have worse employment outcomes without treatment than those who participate in the programme with or without the intervention under investigation. This suggests that the earlier assignment policy of the caseworkers was inefficient in that the always-participants were neither those unemployed who would experience the highest expected treatment effects nor those unemployed who had the largest need for assistance.
This paper develops a nonparametric methodology for treatment evaluation with multiple outcome periods under treatment endogeneity and missing outcomes. We use instrumental variables, pre-treatment characteristics, and short-term (or intermediate) outcomes to identify the average treatment effect on the outcomes of compliers (the subpopulation whose treatment reacts on the instrument) in multiple periods based on inverse probability weighting. Treatment selection and attrition may depend on both observed characteristics and the unobservable compliance type, which is possibly related to unobserved factors. We also provide a simulation study and apply our methods to the evaluation of a policy intervention targeting college achievement, where we find that controlling for attrition considerably affects the effect estimates.
This paper discusses the nonparametric identification of causal direct and indirect effects of a binary treatment based on instrumental variables. We identify the indirect effect, which operates through a mediator (i.e. intermediate variable) that is situated on the causal path between the treatment and the outcome, as well as the unmediated direct effect of the treatment using distinct instruments for the endogenous treatment and the endogenous mediator. We examine different settings to obtain nonparametric identification of (natural) direct and indirect as well as controlled direct effects for continuous and discrete mediators and continuous and discrete instruments. We illustrate our approach in two applications: to disentangle the effects (i) of education on health, which may be mediated by income, and (ii) of the Job Corps training program, which may affect earnings indirectly via working longer hours and directly via higher wages per hour.
In this paper, we quantify the effects of the Earned Income Tax Credit (EITC) from a macroeconomic perspective. We analyze jointly the labor supply and saving responses to changes in tax credit generosity and their aggregate and distributional implications. Our results show that the EITC raises labor force participation, provides insurance to working poor households but also disincentivizes private savings for many. Whilst reducing post-tax earnings inequality, the EITC contributes to a higher skill premium and wealth inequality. Finally, EITC expansions are welfare improving for the majority of the population, both ex ante and when accounting for transitional dynamics.
This paper investigates the efficiency of the matching process between job seekers and vacancy posting firms in West-Germany, using variation across labor market regions and across time. The results of a stochastic frontier analysis shed new light on extent and regional differences of search frictions, on potential determinants of frictional inefficiencies and on the consequences of German reunification for the matching process. The paper also presents novel evidence on the complex interactions between spatial contingencies among regional labor markets: matching efficiency decreases with spatial autocorrelation in hiring, implying indirect evidence for crowding externalities.
We investigate job competition among job seekers and vacancy competition among firms extending the job competition model proposed by Anderson and Burgess (Anderson, P.M., Burgess, S.M., 2000. Empirical matching functions: Estimation and interpretation using state level data. Review of Economics and Statistics 82, p. 90-102). Our results for data from West Germany provide evidence for both phenomena, thereby extending and qualifying previous insights.
"Winner-take-all" markets (i.e., markets in which the relative and not the absolute performance is decisive) have gained in importance. Such markets have a tendency to provoke inefficiently many entries. We investigate such markets in an experiment and show that there are even more inefficient entries than predicted by the Nash equilibrium. Moreover, this effect increases with group size. Quantal response equilibrium predicts the increase in group size but fails to predict the excess entry in the smaller group. We show that the excess entry is not caused by coordination failures. Furthermore, individual entry behavior is not significantly linked to risk preferences.
In this note we consider Cournot oligopoly. Due to the consideration of several consumers and/or technologies, the profit function is not differentiable everywhere. We show that Cournot equilibrium never occurs in outputs where profit functions are not-differentiable. This result validates the procedure of differentiating profit functions to perform comparative statics in models where profit functions are not differentiable everywhere.
Casual evidence as well as daily experience suggest that many people have a strong aversion against being the 'sucker' in social dilemma situations. As a consequence, those who cooperate may be willing to punish free-riding, even if this is costly for them and even if they cannot expect future benefits from their punishment activities. A main purpose of this paper is to show experimentally that there is indeed a widespread willingness of the cooperators to punish the free-riders. Our results indicate that this holds true even if punishment is costly and does not provide any material benefits for the punisher. In addition, we provide evidence that free-riders are punished the more heavily the more they deviate from the cooperation levels of the cooperators. Potential free-riders, therefore, can avoid or at least reduce punishment by increasing their cooperation levels. This, in turn, suggests that in the presence of punishment opportunities there will be less free riding. Testing this conjecture is the other major aim of our paper.
