The balance between observation and measurement

Each morning, at this time of year, I look out of the window to see if I need to leave time to de-ice the car. On the mornings that I forget to do this, I am inevitably delayed by having to scrape ice off the windscreen – just as I was this morning! Winter brings with it cold wind, rain, sleet and snow and, of course, short hours of daylight and the early onset of darkness by late afternoon. Yet, perversely, I look forward to winter, just as I look forward to the arrival of spring, the long hours of daylight, the one hot day of summer and the colours of the trees in autumn. Being from these climes, I enjoy the variation of the seasons. When I have been abroad in sunnier regions for any length of time, I can see that I would become bored of waking up to the sun every day.

However, no matter where we are, the daily, seasonal or other natural cycles impose a period of rest and reflection upon us. Once the door and curtains are closed, the fire is on and I am protected from the elements, I have the opportunity to ruminate at my leisure. One topic that has been raised a number of times recently, and that I now have time to consider, is the relationship between practical observation and analysis through measurement. At first glance, this appears to be a non-topic, because in order to measure you need to observe and, conversely, observation is a measurement of sorts. Notwithstanding, there is often a polarisation in views between these two approaches.

This apparent disconnect between observation and measurement was illustrated in an article in BBC Wildlife magazine. It was reported that a study of sperm whales at the University of Queensland, Australia, had shown that a whale’s head is able to absorb energy from forceful impacts. However, this was not exactly original news: in 1821, the first mate of a ship that had been sunk by a sperm whale commented that the whale’s head was admirably designed for this mode of attack. The university researcher pointed out that it often pays to listen to people who make their living working with animals.

In the late 1800s, Victor Hensen and Ernst Haeckel had a public falling out over their methods of studying plankton. Hensen spent most of his time counting plankton in samples of seawater and claimed that all that mattered were facts, ‘fixed as carefully as possible by weights, measure and number’. Haeckel applied observation and reflection in his studies, spending a lot of time in a boat on the sea collecting samples and describing what he saw.

In the good old black-and-white days of O-Levels, a new teaching method was promoted to make science more interesting to pupils. In preparing for November’s column, I refreshed my memory of Nuffield Science, which I had not been subjected to when at school. The curriculum emphasised the achievement of understanding through hands-on practical work. This had its benefits; it meant that effort was invested in developing new practical and experimental apparatus: the traditional teaching course experiments needed a makeover. Undertaking practical work develops observation and helps to generate questions. However, it had its limitations due to a lack of knowledge of supporting theories, which couldn’t all be obtained from practical exercises. The Nuffield approach to learning still persists today under the terms of discovery learning and inquiry-based learning; it is popular, but there are doubts about its efficacy.

Non-destructive testing is very much a practical discipline. It is no surprise, therefore, that the learning of its application and the assessment of techniques have traditionally been based on practical studies. You don’t have to look too hard to see that the NDT profession has a tendency to polarise along the lines described in the examples above: practitioners and academics; observers and measurers. Yet it is just as easy to see in the examples above and within the profession that the best, and most fruitful, approach is to combine the two in an appropriate manner: Hensen and Haeckel were both correct in some of their conclusions and both wrong in others.

Technology is adding complexity to the application of NDT, with the consequence that a solely practical-based approach can lead to errors. Luckily, technology has also enabled the development of theoretical models, which can be used to plug this hole. Inspection qualification bridges the gap between observation and measurement but, because it has gained an unjustified reputation of being unnecessarily expensive, is implemented with reluctance. Rather than continuing in this introverted impasse, we could benefit from looking at the medical profession with its initiative of evidence-based practice. This is based on three principles: the best available research evidence bearing on whether and why a treatment works; clinical expertise (clinical judgment and experience) to rapidly identify each patient’s unique health state and diagnosis, their individual risks and the benefits of potential interventions; and client preferences and values. Substitute NDT for treatment and clinical, component for patient and plant owner for client and you have a way of working that combines observation and measurement.

NDT will always benefit from the input of ‘first mates’ but, with the introduction of the BINDT NDT Engineer apprenticeship, I believe that we will develop a cadre of personnel who will ensure that the profession acquires the benefit of both observation and measurement. I wish you and your families a happy New Year.

Please note that the views expressed in this column are the author’s own personal ramblings for the purpose of encouraging discussion within the NDT Newspaper. They do not represent the views of Amec Foster Wheeler or the HSE who funded the PANI projects.

Letters can be mailed to The Editor, NDT News, Midsummer House, Riverside Way, Bedford Road, Northampton NN1 5NX. Fax: +44 (0)1604 438300; Email: or email Bernard McGrath direct at

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