This article looks into the processes and outcomes of setting up and maintaining
a probability-based longitudinal online survey, which is recruited
face-to-face and representative of both the online and the offline population
aged 16–75 in Germany. This German Internet Panel studies political and
economic attitudes and reform preferences through bimonthly longitudinal
online interviews of individuals. The results presented here demonstrate
that a carefully designed and implemented online panel can produce highquality
data at lower marginal costs than existing panels that operate solely
in a face-to-face mode. Analyses into the representativeness of the online
sample showed no major coverage or nonresponse biases. Finally, including
offline households in the panel is important as it improves the representation
of the older and female segments of the population.
