News Release

Contact: Alexandra Nseir, (202) 819-4122

Evaluating and addressing biases in non-probability samples, topic of the upcoming 29th annual Morris Hansen Lecture

WASHINGTON, Feb. 22, 2022 – The U.S. Department of Agriculture’s (USDA) National Agricultural Statistics Service (NASS) will host the 29th Annual Morris Hansen Lecture via Zoom webcast on Tuesday, March 1 from 3:30-5:30 p.m. EST. The Washington Statistical Society established the lecture series to honor Morris Hansen and his pioneering contributions to survey sampling and related statistical methods during his long and distinguished career at the U.S. Census Bureau.

This year, the lecture will be presented in a panel format. It is free and open to the public. Register for the event and learn about past lectures.

The panelists include Courtney Kennedy, director of survey research, Pew Research Center; Yan Li, professor, Joint Program in Survey Methodology at the University of Maryland; and Jean-Francois Beaumont, senior statistical advisor, Statistics Canada. Panelists will individually present abstracts on the event topic before engaging in a panel discussion and question-and-answer session.

Kennedy’s presentation, “Exploring the Assumption That Online Opt-in Respondents Are Answering in Good Faith,” highlights findings from several Pew Research Center studies examining the sincerity and accuracy of online opt-in data. The presentation will focus on subgroups where insincere responses are concentrated and errors (measured against federal benchmarks) are particularly large. The presentation considers the magnitude of these errors relative to those observed in online probability-based samples as well as the implications for practitioners.

Li’s presentation, “Exchangeability Assumption in Propensity-Score Based Adjustment Methods for Population Mean Estimation Using Non-Probability Samples,” reviews different exchangeability assumptions under propensity score-based weighting and matching methods and propose an adapted exchangeability assumption.

Beaumont’s presentation, “Reducing the bias of non-probability sample estimators through inverse probability weighting with an application to Statistics Canada’s crowdsourcing data,” focuses on inverse probability weighting methods, which involve modelling the probability of participation in the non-probability sample.

The Morris Hansen Lecture series is one of many public education and outreach activities in which USDA NASS participates. The event is sponsored by the Washington Statistical Society, USDA NASS and Westat, Inc.


NASS is the federal statistical agency responsible for producing official data about U.S. agriculture and is committed to providing timely, accurate and useful statistics in service to U.S. agriculture.

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