I have a data which has a time for wating and service togather, I can't identify the service time. What I have done to calculate the service time for each task. I have calculate the time between the time of output from the service activity and assume that is the service time for each customer. e.g.,
task time of output service time
1 08:20 ?
2 08:30 0:10
3 09:00 0:30
4 10:00 1:00
Is this process correct to calculate the service time? note the first one will be ignore due to I have no idea the previous one of the first task