Are VD16 and VD17 continuous?

Do seventeenth-century editions get cataloged in VD17 with the same thoroughness as sixteenth-century editions get cataloged in VD16? The VD17 database is a younger project than VD16, so one might wonder if the cataloging has not have advanced as far. If that were the case, we might expect to see a plunge in the number of editions recorded in VD16/17 between 1600 and 1601. This sudden decline would be an artifact of bibliography, however, rather than a reflection of actual conditions in the German book trade at the turn of the seventeenth century. It would be useful to know about this accident of bibliography to prevent ourselves from misinterpreting data, for example by thinking that we observe a decline in some segment of the publishing industry between 1590 and 1610 that had no actual historical basis.

So, is the transition from VD16 to VD17 smooth or continuous? The answer is: smooth.

Figure 1: Editions recorded in VD16 and VD17, 1590-1610 (total and by format)

VD17 seems to have caught up with VD16 enough that no discernible gap exists between the two. Here is the graph of total editions (orange) and a breakdown by format (folios, quartos, and octavos are blue, grey, and orange, respectively). Between 1600 and 1601, nothing interesting happens. (The jump in total editions in 1602 that isn't reflected in the individual formats is based primarily on a rise in duodecimo editions and editions without format data, by the way.)

An earlier look at the transition of incunable editions printed in Germany (as recorded in ISTC and GW) to early sixteenth-century editions in VD16 also found no gap.