Despite the extensive use of web surveys today, there are certain methodological factors related to participant cooperation and data quality, which remain unclear and require further study. Here, the authors compare responses to a survey administered in two formats—electronic or by post—in terms of overall response rate and the quality of the data collected. Web and mail questionnaires were sent to a sample of 572 PhD holders, asking them about aspects related to their academic career and personal and family data to investigate the factors that determine scientific productivity. The web questionnaire elicited a significantly higher response rate than the mail questionnaire. Response rates did not differ between males and females; however, topic salience had an effect on the response rate. Finally, data quality was higher in web surveys than in the mail surveys, with fewer overall errors, fewer missing items, and longer responses in open-ended questions.