Today, depending on topic, goal and budget, all kinds of sampling methods are being used, in order to collect consumer data for research in the wine business. However, it is questionable which survey method is able to generate data that does represent the entire population. A representative...

High-worth individuals are typically underrepresented or completely missing in population surveys. The lack of a register-based sampling frame on high-worth individuals in many countries challenged previous attempts to sample high-worth individuals in voluntary scientific surveys. In a novel...

Statistical analysis in surveys is generally facing missing data. In longitudinal studies for some missing values there might be past or future data points available. The question arises how to successfully transform this advantage into improvedimputation strategies. In a simulation study the...

We propose a new view of initial nonresponse bias in longitudinal surveys. Under certain conditions, an initial bias may "fade-away" over consecutive waves. This effect is discussed in a Markovian framework. A general contraction theorem for time inhomogeneous Markov chains is presented. The...