(Un)available upon request: field experiment on researchers' willingness to share supplementary materials.

This article reports results of a field experiment in which two hundred e-mails were sent to authors of recent articles in economics that had promised to send the interested reader supplementary material, such as alternative econometric specifications, "upon request." The e-mails were sent either by a researcher affiliated at Columbia University, New York or the University of Warsaw, Poland; furthermore, the authors' position (assistant professor) was specified in half the e-mails only. Overall, 64% of the approached authors responded to our message, of which two thirds (44% of the entire sample) delivered the requested materials. The frequency and speed of responding and delivering were very weakly affected by the position and affiliation of the sender. Gender or affiliation of the author, number of citations or journal impact factor or the type of object in question seemed to make no difference. However, authors of published articles were much more likely to share than authors of working papers.