Finally, the study design was based on a pre-post comparison of error rates. A randomized controlled trial design was not possible with such a large systemwide intervention.However, the pre- and postintervention periods
were temporally close, and no other significant changes
were made in the medication-dispensing process during the transition to bar coding. Furthermore, no significant changes were noted in other pre-post measurements, such as dispensing volume, case mix and severity,
or prospective payment rates.