Wagner, James, Kristen Olson, and Minako Edgar. “The Utility of GPS Data in Assessing Interviewer Travel Behavior and Errors in Level-of-Effort Paradata”. Survey Research Methods 11, no. 3 (October 20, 2017): 218–233. Accessed April 19, 2024. https://ojs.ub.uni-konstanz.de/srm/article/view/6794.