Joachim Engel is a professor emeritus of mathematics and mathematics education. He received a diploma in mathematics from the University of Bonn and a Ph.D. in applied mathematics from the University of Southern California. Early on, he was fascinated by the mathematics of uncertainty. Over the years his focus shifted from orthodox theory of probability and statistics towards bridging human understanding and sense making in situations of risk and uncertainty.

Andrew Mercer is a senior research methodologist at Pew Research Center. He is an expert on probability-based online panels, nonprobability survey methods, survey nonresponse and statistical analysis. His research focuses on methods of identifying and correcting bias in survey samples. He leads the Center’s research on nonprobability samples and co-authored several reports and publications on the subject. He also served on the American Association for Public Opinion Research’s task force on Data Quality Metrics for Online Samples.

Principal, ValueMetrics, Sydney Australia and School of Mathematics & Statistics University
of Sydney