* 336 mails per day
* AHT = 480 seconds
* SLA is 80% in 4 hours (14400 secs)
Result gives me roughly 8.6 FTE (once I factor in 85% occupancy and 19.5% shrinkage and a workday of 9 hours), which I validated using this site's Erlang calculator.
The challenge I have is that when I change the SLA component from 80% in 4 hours to 12 hours, the FTE requirement only drops to 8.4 FTE. If I change it to 48 hours, it doesn't change at all from 8.4 FTE.
I need to be able to either confirm if this is correct or not, and if it's correct, be able to explain why it's correct. On face value, if I want to answer emails in 4 hours versus 48 hours, surely I'm going to need more people, so why doesn't the formula reflect that? Or am I missing something fundamental?
I've never tried to work this out before as my background has been pretty much voice, so any help would be greatly appreciated.