Ren, Weijia, Tom Krenzke, Brady West, and David Cantor. β€œAn Evaluation of the Quality of Interviewer and Virtual Observations and Their Value for Nonresponse Bias Reduction ”. Survey Research Methods 16, no. 1 (April 10, 2022): 97–131. Accessed April 26, 2024. https://ojs.ub.uni-konstanz.de/srm/article/view/7767.