Social network analysis is typically used where data are complete and all connections within a system are known. However, as other humanities networking projects have discovered, building a network based on historical data means that we are inevitably working with incomplete information. In other words, the lack of connections in our graph doesn’t mean that no connection exists, but only that we have no documented evidence of one. For a large-scale, historical project like the Republic of Letters, this incomplete information is due to the historic nature of the content they are working with; in other words, not all of the evidence exists any more. In our case, we have a different bias and different missing data because we have primarily used information from a single archive as the source of our network data