Is there a Superior Distance Function for Matching in Small Samples?
Eva Dettmann, Claudia Becker, Christian Schmeißer
Abstract
The study contributes to the development of ’standards’ for the application of matching algorithms in empirical evaluation studies. The focus is on the first step of the matching procedure, the choice of an appropriate distance function. Supplementary o most former studies, the simulation is strongly based on empirical evaluation ituations. This reality orientation induces the focus on small samples. Furthermore, ariables with different scale levels must be considered explicitly in the matching rocess. The choice of the analysed distance functions is determined by the results of former theoretical studies and recommendations in the empirical literature. Thus, in the simulation, two balancing scores (the propensity score and the index score) and the Mahalanobis distance are considered. Additionally, aggregated statistical distance functions not yet used for empirical evaluation are included. The matching outcomes are compared using non-parametrical scale-specific tests for identical distributions of the characteristics in the treatment and the control groups. The simulation results show that, in small samples, aggregated statistical distance functions are the better
choice for summarising similarities in differently scaled variables compared to the
commonly used measures.
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Efficiency of qualification and job creating measures in East Germany
Annette Bergemann, Birgit Schultz
Wirtschaft im Wandel,
No. 9,
2000
Abstract
This paper evaluates job creation schemes and further training in East Germany for the period 1990-1998. We identify the causal effect of the treatment-on-the-treated by a two-step procedure: First, we apply the matching technique based on estimated propensity scores. Secondly, we use the Difference-in-Differences estimator. Hereby, we take especially consideration on Ashenfelter s Dip, which characterize a significant decrease in the participants employment shortly before the start of a program. This can be assumed to be related to the anticipation of the participation.
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