How exactly is this calculated, and what is it supposed to indicate regarding public risk or threat?

This 15% for 7 days I am seeing seems vague and arbitrary. Is it based on some statistical analysis that indicates this metric at this duration represents some sort of statistical breakpoint in public risk, or is it a conjecture or intuition based metric that sounded good to whoever drafted the rule?

Apparently it is a calculation, in an area, of the percentage of CoVID positive test hospitalizations relative to total listed hospital beds, but I still haven't found the exact metric as specified in law or regulation and the data sources it uses for daily calculations. I'm really curious what this number means in application. When local or regional hospital bed occupation hits 15% CoVID patients, does it statically begin to increase the impediment of operations or successful treatment outcomes for all patients? Why not 12% or 20%? I'm just curious what the mathematical basis for the metric is.

From my colleagues who run other hospitals, when your census starts to approach 50% COVID things start to get get hairy from an operations persepective. It changes your staffing, your turnover everything.

The 15% came from the fact that someone told the governors that hospitals run on average at 85% capacity so that 15% COVID patients I. House would theoretically put everyone at 100%