I am making a simulation for a mechanics garage. I need to count the number of cars unfinished at the end of the day (cars that do not leave the model). I can calculate this by subtracting the number exiting from the number entering the model but I want to analyse the confidence interval just for the difference. Otherwise, it is too confusing to analyse the risk of a car not finished by the end of the day if i have 2 objects to analyse (cars in and cars out).
Thanks for your help.