Average wait four minutes. Tuesday wait fourteen. The average is true and it is hiding the entire problem.
ArithmeticAnswered483 views
Eight weeks of counts at the student services desk.
Mean wait across everything is 4 minutes 10. I was going to write that down and move on.
Split by day and Tuesday is 14 minutes, every Tuesday, no exceptions. The other four days are between two and three minutes.
Nobody waits four minutes at this desk. Four minutes is the number that makes Tuesday disappear.
Marked as the answer
Then stop reporting the mean on its own. Report the mean, the spread and the worst tenth, every time. A service desk that is fine on average and unusable on Tuesdays is a service desk that fails, and the mean is the number that hides it. This is most of week 9.
Worth saying out loud that the people who get the fourteen minutes are probably the same people every week, because they come when they can, not when it is quiet.
That sentence is the course. Put it in your report.