Rethinking “Distance From”: Lessons from Wittenberg and Mainz

An influential literature in early modern economic history uses “distance from” as an instrumental or a control variable. I show that “distance from Wittenberg” and “distance from Mainz,” two prominent instruments for the adoption of Protestantism and printing technology, have historical and econometric drawbacks that engender misleading conclusions. Historical data challenge the assumption that distance determined access to ideas or technology. Placebo tests and simulations reveal that “distance from” variables frequently produce falsely significant estimates in first stage and OLS regressions. My findings suggest caution in using “distance from” instruments for the adoption of ideas and technologies.