Table 4.

Outcomes by alert type for the randomized set scenarios

	Outcomes for randomized set scenarios (n=504 tasks)
Alert type	Number of errors (rate)
Modal	17 (10.1%)
Non-modal	46 (27.4%)
No alert (control)	87 (51.8%)
Totals	150 (29.8%)

It is possible that the external interruptions to the experimental sessions of four participants (see Participant characteristics) had important effects on the outcomes recorded in those cases. We therefore present a repeat of this analysis that excludes the data of the participants whose sessions were interrupted (online appendix C). The same result is still obtained.