Dittmar's research is “Information Technology and Economic Change: The Impact of the Printing Press”. The abstract reads:
The movable type printing press was the great innovation in early modern information technology, but economists have found no evidence of its impact in measures of aggregate productivity or income per person. This paper examines the technology from a new perspective by exploiting city-level data on the establishment of printing presses in 15th century Europe. I find that between 1500 and 1600, cities where printing presses were established in the late 1400s grew at least 60 percent faster than similar cities which were not early adopters. I show that cities that adopted printing in the late 1400s had no prior growth advantage and that the association between adoption and subsequent growth was not due to printers anticipating city growth or choosing auspicious locations. These findings imply that the diff usion of printing accounted for between 20 and 80 percent of city growth 1500-1600. They are supported by historical evidence and instrumental variable regressions that exploit distance from Mainz, Germany — the birth place of printing — as an instrument for early adoption. The printing press reduced the costs of transmitting information between cities, but fostered new face-to-face interactions and localized spillovers. Print media notably fostered the development of skills, knowledge, and innovations valuable in commerce.