Academic Report of School of Mathematical Sciences [2026] No. 085

(Series Report for High-Level University Construction No. 1344)

Title：Recent Advances in Boxplots for Outlier Detection

Speaker：Professor Tong Tiejun(Hong Kong Baptist University)

Time：15:00-15:50, Sept. 12, 2026

Location：Room 601, Huiyan Building, Yuehai Campus

Abstract: The boxplot, introduced by John Tukey, is a cornerstone of data visualization and outlier detection, but its classic "1.5×IQR" rule does not account for sample size and often mislabels outliers in large datasets. In this talk, I present new advances in boxplots for outlier detection, including the Chauvenet-type boxplot, which unifies the intuitive graphical approach of Tukey’s boxplot with the sample-size-adaptive threshold of Chauvenet’s criterion. This new method delivers robust and principled error control, outperforming traditional approaches and avoiding over-flagging across a range of settings. I will demonstrate these advantages using simulations and a real case study of civil service pay in Hong Kong, and introduce the userfriendly "ChauBoxplot" R package, now available on CRAN, to make these methods accessible to practitioners.

Speaker Profile：Tong Tiejun is a professor in the Department of Mathematics at Hong Kong Baptist University. He received his Ph.D. from the University of California, Santa Barbara, in 2005; conducted postdoctoral research at Yale University from 2005 to 2007; served as an assistant professor at the University of Colorado Boulder from 2007 to 2010; and has been with the Department of Mathematics at Hong Kong Baptist University since 2010. His primary research interests include nonparametric regression models, high-dimensional data analysis, meta-analysis, and evidence-based medicine. He has published more than 100 academic papers in internationally renowned journals such as JASA, Biometrika, Statistical Science, JMLR, and Nature Communications, including several ESI Hot Papers and ESI Highly Cited Papers; his most-cited paper has been cited more than 12,200 times.

Faculty and students are welcome to attend!

Invited by: Zhou Yan

School of Mathematical Sciences

September 9, 2026