Grace Y. Yi is the SSC Gold Medal recipient 2025. Grace is professor and Tier I Canada Research Chair in Data Science at the University of Western Ontario, where she holds a joint appointment in the Department of Statistical and Actuarial Sciences and the Department of Computer Science. She joined Western in July 2019 after nearly two decades at the University of Waterloo, where she began as a postdoctoral fellow in January 2000 and held positions as assistant professor (2001–2004), associate professor (2004–2010), full professor (2010–2019), and university research chair (2011–2018).
Born in Sichuan province, China, Grace obtained her bachelor's degree in mathematics from Sichuan University in 1986, and a master’s degree in mathematics, specializing in topology, from the same university in 1989. She then taught advanced mathematics at the University of Electronic Science and Technology in China for 6 years before moving to Canada in 1995 to pursue graduate studies in statistics. She obtained her MSc in statistics from York University in 1996 and her PhD in statistics from the University of Toronto in 2000, under the supervision of Don Fraser. Her thesis, “On the Structure of Asymptotic Distributions,” laid the foundation for her deep engagement with theoretical statistics. During her PhD studies, she also worked with Nancy Reid as a research assistant for the book The Theory of the Design of Experiments.
Although her initial encounters with statistics were marked by dislike or even aversion, her doctoral studies completely transformed her perspective. With the inspiring mentorship of Don Fraser and Nancy Reid, she moved from struggling with concepts such as confidence intervals to becoming immersed in statistical research. Her brief but intense 39-month stay at the University of Toronto led her into what she now calls “the wonderland of statistical science.”
Grace began her postdoctoral fellowship at the University of Waterloo and subsequently joined the faculty there. Collaborating with eminent scholars including Richard Cook, Jack Kalbfleisch, Mary Thompson, and Jerry Lawless, she focused on developing new methods for missing data, data measured with error, survival data, and longitudinal data. This productive period marked the beginning of her long-standing commitment to methodological development in statistics and biostatistics.
Her contributions to the field are both foundational and far-reaching. Internationally recognized as a leading expert in measurement error and missing data, Grace was among the first to address the intertwined complexities of these issues by introducing a unified framework. These aspects of noisy data—individually challenging and even more so in combination—present serious barriers to valid inference and model development. Grace’s pioneering work in this space has influenced a broad range of applied and theoretical research. She is the author of the monograph Statistical Analysis with Measurement Error or Misclassification: Strategy, Method, and Application (Springer, 2017) and coeditor of the Handbook of Measurement Error Models (with Aurore Delaigle and Paul Gustafson, Chapman & Hall/CRC, 2021). Beyond data quality, Grace has made substantial contributions to foundational statistical inference methods, including composite likelihood theory, estimating functions, likelihood-based inference, causal inference, and high-dimensional data analysis. She is coauthor of the monograph Likelihood and its Extensions (with Nancy Reid and Cristiano Varin, Chapman & Hall/CRC, 2025).
Since joining Western, Grace has expanded her research into machine learning, with a focus on statistical methods that address modern data challenges related to label noise, missing data, source-free domain adaptation, transfer learning, boosting, and deep learning. Her work at the intersection of statistical science and machine learning has led to robust methodologies for analyzing noisy and incomplete data, bringing new insights and perspectives to the field.
A passionate educator and mentor, Grace has mentored many postdoctoral fellows and MSc students and has supervised 23 PhD students—three of whom have received the prestigious Pierre Robillard Award from the Statistical Society of Canada. In 2023 her efforts were recognized with the Award for Excellence in Graduate Student Mentoring by Western.
Grace is a fellow of the Institute of Mathematical Statistics and the American Statistical Association, and an elected member of the International Statistical Institute. She received the CRM-SSC Prize in 2010, which honours outstanding research in the first 15 years after earning a doctorate. She held an NSERC University Faculty Award from 2004 to 2009. Her paper with Xianming Tan and Runze Li was awarded the Canadian Journal of Statistics Award in 2016. In 2025 she delivered the Myra Samuels Memorial Lecture at Purdue University.
Grace is a leader in advancing statistical science both nationally and internationally. She served as coeditor in chief of the Electronic Journal of Statistics (2022–2024), editor in chief of the Canadian Journal of Statistics (2016–2018), and is currently serving as editor of the methodology section of the New England Journal of Statistics in Data Science. She has served as president of the Statistical Society of Canada (2021–2022) and president of its Biostatistics Section (2016), and as chair of the Lifetime Data Science Section of the American Statistical Association (2023). In 2012 she founded the first chapter of the International Chinese Statistical Association (ICSA)—the Canada Chapter.
Grace credits much of her success to her collaborators and students. She is especially grateful to her family, who have been a continuous source of inspiration and strength. She holds deep gratitude for their love and encouragement—her husband, Wenqing He, a valued research collaborator and a patient and unwavering supporter; and her children, Morgan and Joy, for their tremendous love and support in countless ways.
The citation for the award reads:
“In recognition of an impactful and extensive body of research on statistical theory and methodology, with a special focus on missing and mismeasured data and applications in biostatistics; and for her leadership in statistical science in Canada.”