It’s even simpler. A strictly increasing series will always have element n be higher than the average between any element<n and element n.
Or in other words, if the number of calls is increasing every day, it will always be above average no matter the window used. If you use slightly larger windows you can even have some local decreases and have it still be true, as long as the overall trend is increasing (which you’ve demonstrated the extreme case of).
It’s even simpler. A strictly increasing series will always have element n be higher than the average between any element<n and element n.
Or in other words, if the number of calls is increasing every day, it will always be above average no matter the window used. If you use slightly larger windows you can even have some local decreases and have it still be true, as long as the overall trend is increasing (which you’ve demonstrated the extreme case of).
It’s even simpler. They just lie about and always say it’s higher than average.