Number entry error
Number entry errors are errors in number entry. Simple number entry errors are known to cause adverse patient events, including fatal ones. Inappropriate number entry, such as entering two decimal points within the same number, may not produce an error message even though it has created a dangerous deviation from the intended input(1). This deviation may not be obvious to the user even though it is dangerous to the patient. A device or system may even produce different results from a number entry error depending on the state the system was in when the error occurred(1).
Introduction
Humans err frequently and often in a predictable fashion. Unfortunately, many information systems, clinical and otherwise, are designed as if entry errors are rare or unknown. Using what is known about number entry error to design more robust systems would be a better practice.
A significant part of User Interface Design (UID) includes detecting and preventing user number entry errors. This is often accomplished through the use of error messages, which, if well designed, can alert the user to the type of error which was made allowing him/her to correct it and possibly even avoid that error in the future. Obviously no system can prevent all number entry error. Spell check provides a useful analogy – if one types the wrong word (enters the wrong number) but spells it correctly (makes no syntax errors in entering the number) the system will not detect the error.
A highly successful means of avoiding human error in number entry is to remove the need for a human to enter the number at all. As systems become more integrated, this will become more common.
References
- Thimbleby, H Paul Cairns, P. Reducing number entry errors: solving a widespread, serious problem. J. R. Soc. Interface (2010) 7, 1429–1439
- Institute for Safe Medication Practices. 2006 List of error prone abbreviations, symbols and dose designations. See www.ismp.org/tools/abbreviations.
