Abstract
The success of a discrete event simulation project relies heavily on input data quality. In order to achieve high quality data a significant amount of time needs to be spent, either due to absence of data or problems with defining and extracting existing data from databases. This paper presents a distribution of the time-consumption for the activities in the input data phase during discrete event simulation projects. The results show where efforts need to be focused to reduce time-consumption and improve quality of input data man-agement.