e.g. if nobody ever leaves the company, but you always double the number of employees every year by very aggressive hiring, the average tenure according to that metric is 1 year.
However, it's also unclear exactly how 1.1 number is calculated. It looks like it comes from PayScale, which doesn't give, as far as I can tell, a methodology:
Is that the median amount of time that all current employees have had with the company so far?
Or is it the median of all of the employees that used to work there & moved on, which would exclude people that have continued to work there?
Or is it some type of survival analysis that takes such factors into account?
