Average number of leaves in German practicas, 1480-1620
Generating this graph was one of the benefits of entering every edition that was relevant for Printing and Prophecy into a Microsoft Access database. Once the data was there, it was easy to select only the German practicas, drop the format field into an Excel spreadsheet, and turn the various format formulations into leaf counts through a combination of Excel formulas and manual editing. (An example from VD16 is " Bl. : TH. ; 4"; it's not too difficult to tell Excel to grab only the parts between the square brackets.)
The following table summarizes how many practicas from each decade had known leaf counts (so excluding fragments), and the average as seen in the graph above.
And thus five years of intermittent data collection and an hour of fiddling with a database query and a spreadsheet yields three sentences of expository prose and one neat graph that didn't make it into print.