What Shall We Do With the Unseen Sailor? Estimating the Size of the Dutch East India Company Using an Unseen Species Model

Historians base their inquiries on the sources that are available to them. However, not all sources that are relevant to the historian’s inquiry may have survived the test of time. Consequently, the resulting data can be biased in unknown ways, possibly skewing analyses. This paper deals with the Dutch East India Company its digitized ledgers of contracts. We apply an unseen species model, a method from ecology, to estimate the actual number of unique seafarers contracted. We find that the lower bound of actual seafarers is much higher than what the remaining contracts indicate: at least, thirty-six percent of the seafarers is unknown. Moreover, we find that even in periods when few records survived, we can still credibly estimate a lower bound on the unique number of seafarers.