Science blog

07 April 2015

The Importance of Understanding Number Entry

EThOS at the British Library and our partners Research Councils UK and Vitae recently ran our inaugural #ShareMyThesis competition. The competition challenged PhD students past or present to summarize why their research is/was important in 140 characters or less. For more information see the competition webpage here.

The overall winner was Sarah Wiseman who succinctly conveyed the importance of her PhD research at UCL in the following tweet:

Here we re-post Sarah’s winning article:

Have you ever dialled a phone number incorrectly and ended up talking to the wrong person on the end of the line? Most people have, and it can be a little embarrassing (although occasionally it has been known to result in romance). Now, have you ever typed a number wrongly when setting up a bank transfer? That’s a bit more annoying, and many people have lost a lot of money by sending it to the wrong person. But that’s only money. Sometimes the consequences of number entry error can be even more severe: when a doctor or nurse types a number incorrectly into a medical device the patient can receive a serious overdose. This, unfortunately, is not a rare occurrence, and there are regularly cases reported in the news of a number entry error resulting in the harm or even death of a patient.

Often in the media the response is to blame the nurse or doctor for being sloppy. This reaction means that medical workers can themselves become victims of the incident as they are portrayed as being solely responsible for the otherwise avoidable death of a patient.

Although they have different consequences, the reasons we make errors when typing numbers in the hospital is no different from when we dial the wrong phone number. Sometimes we just make an error when entering numbers because humans are fallible and are even more so when asked to work in high-stress environments such as the hospital. Blaming the medical workers involved in these cases will not help to prevent future errors from happening.


One way to reduce the number of these tragic incidents from occurring is to improve the design of medical devices. It has been shown that some number entry interfaces found on medical devices, such as those used to administer drugs to patients, can be unpredictable. Other interfaces obscure key numbers from users, making it difficult for them to notice any errors they’ve made. In safety critical situations it is important the device interfaces are as intuitive and easy to use as possible.These systems are poorly designed partly because we haven’t understood how people type numbers. It is for this reason that I focussed on understanding how users transcribe numbers in my PhD thesis. During my research I was able to show that there are patterns in the numbers entered by medical workers when programming some devices, and that these patterns affect the way that the numbers are transcribed. These common numbers have so far been overlooked when testing number entry interfaces. By incorporating this information into the testing process, interfaces can be examined in more realistic ways.

It isn’t just testing practices that could be improved however; the design of the number entry interfaces themselves can also be altered. Further research in my PhD showed that adapting the interfaces to match these regularly used numbers significantly reduced the number of key presses required, which could reduce the opportunity for error.

These were just a few insights from my PhD work, but they highlight that current practices in number entry research and design stand to be updated and improved. Knowing more about the number entry task can allow for more thorough and accurate testing of interfaces. This would mean that they could be made as error proof as possible. Hopefully by incorporating the number entry research that both myself and others are doing, medical devices in the future can be designed with the user in mind. In doing so we might be able to reduce the occurrence of avoidable, and life altering errors.

Sarah completed her PhD with Anna Cox at UCL’s Interaction Centre. Her work was funded by UCL Psychology and Languages Department with additional funding from EPSRC through the CHI+MED project. Her thesis is available here. Sarah is now working as a post doctoral researcher based at both University College London and the Open University. At the OU she is working on a project that aims to explore how technology can improve accessibility to the arts for people with visual impairments. At UCL she is continuing her PhD topic by researching number entry error and the possible causes.


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