A Closer Look at Precision: Interview with John Helliwell on the Latest IUCr OUP Teaching Text

Below is an interview with the author, John R Helliwell, conducted by Jacqui Gulbis. 

Jacqui Gulbis: Why did you write this book?
John R Helliwell: Newcomers to the field of structural biology, which aims to understand life at the molecular level, see a vast array of existing results and are faced with a diverse range of experimental methods that can be used singly or in various combinations. Unfortunately, the uncertainties of published results are rarely fully analysed and reported. Numerous types of data are even given with a false precision. Results can be described as accurate when, in a physicist’s terminology, precision is meant. If you type the words “precision and accuracy” into Google images, numerous examples are given of a dartboard with a tight cluster of darts away from the bull’s eye meaning good precision but poor accuracy, and a poor distribution of darts but around the bull’s eye to mean poor precision but good accuracy. The only difficulty in science is that we don’t know where the bull’s eye actually is, i.e. the “truth”. As scientists we are aware that, while we may not know the absolute truth, our approximation to scientific truth is in the raw data, our processing of it, and the model we finally derive. That is our equivalent of the courtroom’s “the truth, the whole truth and nothing but the truth”. In biology we know that the truth is the living cell; however, we cannot observe the inside of the living cell in atomic detail. Furthermore, in assessing atom movements upon some sort of stimulus we need to assess the uncertainties in their starting and final positions and indeed if they are moving at all in our time-resolved experiments.

On a less lofty level, also to say, that while I was preoccupied with new synchrotron radiation and neutron instrumentation, methods and structural applications, my collaborator and mentor Durward Cruickshank stimulated my interest in crystal structure model refinement in general and model precision in particular. I have dedicated my new book to him.

What is your book about?
As a teaching text I start by describing the basics of what precision and accuracy are. Also, I assess all the methods that we harness in structural biology, which means properly describing the uncertainties in our results for each one of them. These methods include crystallography, diffraction and scattering using various probes (X-rays, electrons and neutrons) as well as the microscopies and spectroscopies. In combination, these provide powerful glimpses of the scientific truth of the living cell. By “powerful”, I mean that it can guide interventions, helping the pharmaceutical industry in solving pathologies and diseases. My book also covers the topics of predictions and molecular dynamics simulations.

Who are you aiming at?
Principally I am aiming my book at graduate students from a wide range of science disciplines including physics, chemistry, biology, and mathematics. But I think that long time practitioners in the discipline of structural biology will be stimulated in their thinking and practice. It may provoke improvements in our best practice.

When will it be used most?
Our crystallographic societies, national, regional and global, and other representative organisations in biophysics, biochemistry, chemistry and data science who each provide teaching courses on a yearly basis will be a prime audience for my new book. Some universities and colleges do have undergraduate courses on the topics of my book and, as the price of the book is quite low, I also hope it will be purchased by these students to provide a foundation for those courses.

Where will it be used?
The book is in English, which covers a large part of the world obviously, but I hope it will be translated into other languages. OUP is open to being approached by other publishers for Chinese, French, German, Italian, Japanese, Portuguese, Russian, or Spanish versions, for example.

How did you research and write it?
I have a good range of experience across most of the methods I cover, drawn from my experience at synchrotron radiation and neutron facilities, including as a beamline scientist and at senior levels up to facility director, but also running my own wide ranging research laboratory projects. Nevertheless, digging deep across the literature was needed to bring various aspects of my knowledge up to date. I have access to the very splendid University of Manchester Library as an Emeritus Professor. Also, the numerous permissions requests I made to the authors of figures and article quotations often led to interesting dialogues and even my learning about their papers in press.

Tell us about your teaching experience
I have taught crystallography to undergraduate and graduate physicists, chemists and biochemists at Keele, York, and Manchester Universities as well as to early career researchers in Europe and the USA at crystallography society training courses. Students often ask: why am I learning this? I finish each chapter with a short set of “Key learning points”. In addition, I mention that I was a member of the IUCr OUP Book Series Committee from 1996 to 2023, including as its chairman from 2017 to 2023. I had chance to comment on a large number of book proposals, both research monographs and teaching texts, that came to our committee for evaluation. Especially relevant, was that these revealed a range of approaches taken by authors of these teaching texts. This evaluation procedure exposed me to the exceptionally learned members on the IUCr Book Series Committee and thereby their insights from the perspectives of all the sub-disciplines of crystallography.

This book is amongst the least expensive of the IUCr Teaching texts
The price is driven by the length of the book, and I have a tendency to write concisely, which has kept the number of pages down. I benefitted from the senior management training provided to me as a synchrotron facility director. To paraphrase a well-known saying, sometimes attributed to Oscar Wilde: it takes a lot of time to write a concise version. Anyway, I hope it means that the sales of my book will be buoyant, and I mention that I am donating the royalties from the sale of my book to the IUCr Education and Outreach Fund.

Details of the book: Precision and Accuracy in Biological Crystallography, Diffraction, Scattering, Microscopies, and Spectroscopies by John R. Helliwell is the latest book in the International Union of Crystallography Texts on Crystallography Book Series published by Oxford University Press. Available from 01 October 2025, 144 pages and 27 figures. ISBN: 9780198952824. Also available as an e-book.