“Doing my PhD under the supervision of Prof Andriëtte Bekker and Prof Mohammed Arashi was like participating in the popular TV show, Amazing Race – which means that you better run!” This is how Dr Seite Makgai, the first African female lecturer in the Department of Statistics at the University of Pretoria (UP) summarised her PhD journey.

“Prof Bekker, the Head of the Department of Statistics has an eye of seeing the pit stop and Prof Arashi has a different view of what the pit stop looks like. They walk with you all the way and it was a journey that I have been privileged to be on with them,” Dr Makgai explained the analogy. Dr Jaco Visagie was also her co-supervisor, with Professor Daan de Waal (from the University of the Free State) as a regular advisor on her PhD.

Dr Makgai is a New Generation Academic position (nGAP) lecturer who graduated during UP’s recent virtual graduation ceremonies with a PhD in Mathematical Statistics. She is still working with Prof Bekker and Prof Arashi on postdoctoral research in the Department.

“I did my undergraduate studies in Actuarial Sciences and then decided to continue my postgraduate studies in Statistics. I enjoyed statistics on undergraduate level and saw the rare skill that statisticians have of developing mathematics that could answer specific research questions. Distributional theory is a field in Statistics that focuses on building functions that explain and cater to research questions.”

“The title of my thesis is From Beta to Dirichlet Frontiers, and it (the thesis) focuses on both theory and application.  The beta and Dirichlet distributions form the basis/foundation of the theory. The beta distribution is a well-known distribution that is widely used in modelling proportions and probability outcomes. The Dirichlet distribution is a multivariate extension of the beta distribution.  It is well known for modelling compositional datasets (such as the analysis of the proportions of coal quality, size and thickness towards coal production).  It is also used in the world of topic and text modelling (obtaining a topic from analysing the proportion or number of words/text that appears on a document). The challenge here is these distributions fail in modelling current world problems, where there are outliers or extreme cases.”

“In this research, I develop two new models/classes of multivariate distributions that provide a new avenue of modelling a wide range of multivariate compositional data sets, particularly with outliers, specifically within environmental, medical, and social media sectors. I studied the behaviour of each class and presented their unique properties such as particular parameter behaviour and dependence structures for member distributions belonging to these classes. In addition, a new model testing technique is also designed to evaluate the performance of multivariate models such as these.  The research contribution, which originated from the univariate domain and now encompasses the multivariate domain, fulfils the necessity for flexible multivariate distributions that enable practitioners to model a wide range of multivariate data sets. The interesting part of the research is seeing the numbers tell a story for each data set, so I enjoyed the process of linking the application results to the developed theory,” Dr Makgai explained her research.

When asked if she would advise anyone to do a PhD, Dr Makgai declined. Her reason being, “I would tell anyone to follow their internal compass of where they should be and to grow wherever they are placed in life. However, if the prospect of a PhD shows up, then I would say take on the challenge.”

She is elated about finishing her PhD saying, “I am not shocked, but I am surprised that I made it the way I did to the end of this journey. It has not sunk in yet since this year came with its surprises. The person that I was in undergrad would have never believed the possibility of graduating with a PhD. Obtaining a PhD gave me another pair of eyes. It taught me the importance of continuing with learning, finding interest with what is around you and most importantly, finding solid solutions to problems,” Dr Makgai elaborated.

She is the first in her family to obtain a PhD, but not the first doctor. “My sister is a medical doctor as well as a medical researcher for pharmaceutical companies.  My parents were very much into history and the arts, which is different from what their children turned out to pursue,” she concluded sharing her experience of her PhD journey.