Hélène Massam (1949–2020)

 

Hélène Massam, professor of statistics at York University, Toronto, passed away on August 22, 2020 following a cerebrovascular accident. She was 71.

 

Hélène, whose full maiden name was Hélène Menexia Kampouris, was born in Marseille, France, on January 10, 1949. Her parents were humble Greek folk who had emigrated to France before World War II and lived in difficult material and social conditions in the port area. They cherished Hélène, who was their only child, and nurtured her immense talent and the passion for learning that would lead her to live an exemplary life and have a highly successful academic career.

 

Hélène attended the Lycée Montgrand in Marseille, including three years of postsecondary education in the preparatory classes for the Grandes Écoles, France’s elite education institutes known for their highly competitive entrance exams. In 1969 she entered the École normale supérieure de Fontenay-Saint-Cloud, now part of the École normale supérieure de Lyon.

 

 After marrying geographer Bryan Massam in July 1969, Hélène left with him for Montréal, where she chose to study mathematics at McGill University. She completed a BSc (Special Honours) in 1971 and embarked on graduate studies in optimization under the supervision of Sanjo Zlobec. She earned her MSc in 1973 and her PhD in 1977 with a thesis titled “Mathematical Programming with Cones.” It is also during this period that she had her two children, Alexandra (born in 1974) and Laurent (born in 1976).

 

In 1977, the family moved to Ontario, and Hélène joined the University of Toronto, first as a research associate (1977–78), then as a postdoctoral fellow (1978–81), and finally as a lecturer (1981–84). It is there that she developed her interest in statistics with the encouragement of Don Fraser. Their collaboration continued throughout the 1980s and resulted in seven papers which often combined optimization and inference in classical regression contexts, but also on cylinders and spheres.

 

Hélène was hired at York University as an assistant professor of statistics in 1984. She was promoted to the rank of associate professor in 1988 and became a full professor in 1996. York was her academic home for the rest of her career, except for a leave without pay when she was on faculty at the University of Virginia from 1997 to 2001. Her sabbatical leaves also allowed her to travel extensively, notably to France, Italy, and Tunisia.

 

The year 1989 marked a turning point in Hélène’s life. Her couple dissolved, though family life continued unwaveringly. Her research also took a new direction, as signposted by her solo paper in JRSS-B on an exact decomposition theorem for a sample from the trivariate hyperboloid distribution. She started investigating decomposition problems for various classes of exponential families, leading to her first publication in The Annals of Statistics in 1994. Over the years, she would publish a dozen papers in that premier journal.

 

Gradually, Hélène turned her attention to the structural properties of the rich class of Wishart distributions and various inferential issues related to the use of this class of models in practice. A sizeable portion of her research was devoted to this topic. Her main collaborator, Gérard Letac, cosigned over 20 papers with her on related themes and ultimately became her soulmate.

 

With her collaborators, Hélène proved a Craig-Sakamoto theorem and studied various aspects of Wishart distributions on symmetric cones. She looked into quadratic and inverse regression for Wishart models, characterized the normal-Wishart law, derived the moments of the complex Wishart, and addressed the even more delicate case of the real analog. She also investigated the existence of a noncentral Wishart distribution for a continuous shape parameter, designed efficient simulation schemes for the hyper-inverse Wishart and the G-Wishart, and much more.

 

Hélène’s knowledge on Wishart-type distributions eventually led her to contribute to their use in graphical models. She designed Wishart distributions for decomposable graphs, conjugate priors for non-decomposable graphs, reference priors for discrete decomposable graphical models, and so on. She also looked into covariance estimation and various tests for different classes of graphical models.

 

In 2008, Hélène was named a fellow of the Institute of Mathematical Statistics for her contributions to Wishart distributions and graphical models. In subsequent years, she also made numerous contributions to the theory of, and inference for, discrete hierarchical models, looked into high-dimensional issues for this class of models, and used her vast expertise of graphical models in applications, notably in genomics. She was frequently invited to speak at conferences and gave series of lectures in Sfax, Tunisia, and Pau, France. She remained very active until the end and at the time of her passing, she had 64 refereed articles and three book chapters in print; four papers were under review and more work was underway.

 

Over the years, Hélène supervised six MSc students, 10 PhD students, and seven postdoctoral fellows. She was appreciated and respected as an outstanding supervisor who devoted herself to helping her students achieve high expectations. She also mentored many young colleagues and played an active part in the creation of York’s doctoral program in statistics and statistical consulting unit. She served the community at large through the organization of workshops and research programs at the Fields Institute, SAMSI, and CANSSI, among others. She was a member of the founding editorial board of the journal Bayesian Analysis (2004–09), and an associate editor for the Journal of Multivariate Analysis (2010–13) and The Annals of Statistics (2015–19).

 

Quiet and reserved by nature, Hélène was strong and resilient in the face of adversity. She was a woman of culture who enjoyed literature, classical music, and the opera. She was also a mountain hiking enthusiast. Over the years, she had reached a state of inner peace and departed serenely. She left behind her beloved children Alexandra (Martin Choquette) and Laurent (Joanna Swinburne), her grandchildren Katherine and Mathieu Choquette, Alexa, Elise and Luc Massam, her companion Gérard as well as many friends and colleagues. She will be greatly missed.

 

By Christian Genest (McGill University) and Xin Gao (York University)