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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Subsidized Vocational Training: Stepping Stone or Trap? An Evaluation Study for East Germany
Eva Dettmann, Jutta Günther
IWH Discussion Papers,
No. 21,
2009
Abstract
The aim of this paper is to analyze whether the formally equal qualifications acquired during a subsidized vocational education induce equal employment opportunities compared to regular vocational training. Using replacement matching on the basis of a statistical distance function, we are able to control for selection effects resulting from different personal and profession-related characteristics, and thus, to identify an unbiased effect of the public support. Besides the ‘total effect’ of support, it is of special interest if the effect is stronger for subsidized youths in external training compared to persons in workplace-related training. The analysis is based on unique and very detailed data, the Youth Panel of the Halle Centre for Social Research (zsh).
The results show that young people who successfully completed a subsidized vocational education are disadvantaged regarding their employment opportunities even when controlling for personal and profession-related influences on the employment prospects. Besides a quantitative effect, the analysis shows that the graduates of subsidized training work in slightly worse (underqualified) and worse paid jobs than the adolescents in the reference group. The comparison of both types of subsidized vocational training, however, does not confirm the expected stronger effect for youths in external vocational education compared to workplace-related training.
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Are there Gender-specific Preferences for Location Factors? A Grouped Conditional Logit-model of Interregional Migration Flows in Germany
Lutz Schneider, Alexander Kubis
IWH Discussion Papers,
No. 5,
2009
Abstract
The article analyses the question whether women and men differ in their tastes for location factors. The question is answered by quantifying the impact of location characteristics on interregional migration flows across Germany. The analysis is based on a grouped conditional logit approach. We augment the framework by controlling for violation of the independence of irrelevant alternatives assumption and for overdispersion. As a result, we find no differences in terms of direction of impact. However, the regressions confirm gender differences in terms of intensity, particularly regarding regional wage levels and the availability of educational institutions.
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