We start out by performing a Quicktest on Activity 1. According to the specified model, this activity starts January 1., 1996 and finishes 18.3 days later, i.e., on January 19. The start and finish dates are displayed respectively in the input and output fields of the Quicktest dialog box.

In order to calculate the duration of Activity 1 from the start and finish dates, we must remember to include the first day, i.e., January 1 in our case. Thus, we end up with 19 days here. 

This means that the duration can be calculated as the difference between the finish date of Activity 1 and the day before “time zero”, i.e., December 31., 1995 in our case. 

In general the duration of a date node is calculated as the difference between its finish date, displayed in the output field, and the finish date of its predecessors. If the node does not have any predecessors, which happened in our case, the day before “time zero” is used instead.

The duration of a date node is always measured in days, and is displayed in the Local field in the Quicktest dialog box.