Blockmodeling of multilevel networks

•Introduction of three approaches to blockmodeling of multilevel networks.•Separate analysis of the levels and comparison.•Transforming all networks to one level and blockmodeling on this level.•A truly multilevel approach: all levels and ties among them are modeled jointly.•Each approach has its own advantages and disadvantages.

The article presents several approaches to the blockmodeling of multilevel network data. Multilevel network data consist of networks that are measured on at least two levels (e.g. between organizations and people) and information on ties between those levels (e.g. information on which people are members of which organizations). Several approaches will be considered: a separate analysis of the levels; transforming all networks to one level and blockmodeling on this level using information from all levels; and a truly multilevel approach where all levels and ties among them are modeled at the same time. Advantages and disadvantages of these approaches will be discussed.