We know from prior work that there are gaps in the archival record (as with most archives!). Missing logbooks in the 1930s, incomplete borrowing records. shakespeareandco.princeton.edu/analysis/202...

The Shakespeare and Company Lending Library Cards in Context

What is the relationship between the lending library cards and the logbooks?

We use time series forecasting to estimate missing membership activity (subscriptions, renewals, reimbursements) and members and conclude that Shakespeare and Company Project datasets include 93% of membership activity and 96% of members.