Designing for the task: what numbers are really used in hospitals?
In the English language, the letters of the alphabet do not occur with equal frequency. Some letters occur far more often than others, for example the letter
e' occurs more frequently thanz'. In this paper we show that as with letters, digits too su er from unequal distributions in some situations. Here we show that the most common digits being used when programming infusion pumps to administer drugs to patients are 0, 1, 2 and 5. The digit 9 is also frequently used to set an infusion to run at the maximum rate possible. With this information, we evaluate three current forms of infusion pump input with regards to the digits that are actually being programmed into the machines. We argue that the current number interface designs used in medical devices should take into account these findings in order to produce interfaces that are both more suitable for the task, and less error prone in use.