  The way pages are ranked in search results influences whether the users of
search engines are exposed to more homogeneous, or rather to more diverse
viewpoints. However, this viewpoint diversity is not trivial to assess. In this
paper we use existing and novel ranking fairness metrics to evaluate viewpoint
diversity in search result rankings. We conduct a controlled simulation study
that shows how ranking fairness metrics can be used for viewpoint diversity,
how their outcome should be interpreted, and which metric is most suitable
depending on the situation. This paper lays out important ground work for
future research to measure and assess viewpoint diversity in real search result
rankings.
