What’s the point of the PhD thesis?

Julie Gould in Nature:

On the morning of Tom Marshall's PhD defence, he put on the suit he had bought for the occasion and climbed onto the stage in front of a 50-strong audience, including his parents and 6 examiners. He gave a 15-minute-long presentation, then faced an hour of cross-examination about his past 5 years of neuroscience research at the Donders Institute for Brain, Cognition and Behaviour in Nijmegen, the Netherlands. A lot was at stake: this oral examination would determine whether he passed or failed. “At the one-hour mark someone came in, banged a stick on the floor and said 'hora est',” says Marshall — the ceremonial call that his time was up. “But I couldn't. I had enjoyed the whole experience far too much, and ended up talking for a few extra minutes.” Marshall's elaborate, public PhD assessment is very different from that faced by Kelsie Long, an Earth-sciences PhD candidate at the Australian National University (ANU) in Canberra. Her PhD will be assessed solely on her written thesis, which will be mailed off to examiners and returned with comments. She will do a public presentation of her work later this year, but it won't affect her final result. “It almost feels like a rite of passage,” she says.

PhDs are assessed in very different ways around the world. Almost all involve a written thesis, but those come in many forms. In the United Kingdom, they are usually monographs, long explanations of a student's work; in Scandinavia, science students typically top-and-tail a series of their publications. The accompanying oral examination — also called a viva voce or defence — can be a public lecture, a private discussion or not happen at all. There is wide variation across disciplines and from one institution to the next. “It is a complicated world in doctoral education. One format does not fit all,” says Maresi Nerad, founding director of the Center for Innovation and Research in Graduate Education at the University of Washington in Seattle. This isn't necessarily a problem in itself, but some researchers worry that the decades-old doctoral assessment system is showing strain. Time-pressured examiners sometimes lack training and preparation for PhD assessments, which can lead to lack of rigour. “Two or three examiners come together to go through the thesis in a perfunctory way. They tick the boxes, everyone is happy, and then a PhD walks away,” says Jeremy Farrar, director of the biomedical research charity the Wellcome Trust in London.

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