Turning Qualitative into Quantitative Evidence: A Well-Used Method Made Explicit

Many historians now reject quantitative methods as inappropriate to understanding past societies. It is argued here, however, that no sharp distinction between qualitative and quantitative concepts can be drawn, as almost any concept used to describe a past society is implicitly quantitative. Many recent advances in understanding have been achieved by deriving quantitative evidence from qualitative evidence, and using it jointly and dialectically with the qualitative evidence from which it is derived. Its reliability as quantitative evidence can be improved by indexing it against other quantitative evidence from the same community or population during the same period. We suggest that this triangulation method can be extended to many apparently qualitative types of sources that have not previously been used in this way. The potential of turning qualitative into quantitative evidence, then, despite its successes over the past decades, has hardly begun to be exploited.