Nonresponse in surveys may result in a distortion of the distribution of interest. In a panel survey the participation behavior in later waves is different from the participation behavior at the start. With register data that cover also the information for non-respondents one can observe a fade...

This report describes the design, data, and main results of an online survey (i.e., the "Judging Without Knowing" survey) that was conducted between October 2017 and June 2018 with more than 2,000 registered members on Clickworker (a commercial survey company in Germany). The survey was...

We study the relationship between overconfidence and the political and financial behavior of a nationally representative sample. Consistent with theoretical predictions, our findings indicate that excessive confidence in one's judgment is associated with lower portfolio diversification, greater...

This paper investigates if significant differences exist between online and paper & pencil participants in a quarterly business survey in the German business-related services sector when respondents may freely choose to respond either online or by more conventional methods. It also analyzes the...

Die Untersuchung sozialer Ungleichheiten gehört zum Hauptgeschäft der Soziologie. Viele Ursache-Wirkungs-Mechanismen für Ungleichheitsphänomene sind gut erforscht, zumeist existieren alternative oder komplementäre Erklärungen für vorhandene Ungleichheiten. Aus dem Wissen, wie...

We propose a novel view of selection bias in longitudinal surveys. Such bias may arise from initial nonresponse in a probability sample, or it may be caused by self-selection in an internet survey. A contraction theorem from mathematical demography is used to show that an initial bias can...