What is MEDIAN?
You're the first person I have seen in today's articles about HBD to mention the word "MEDIAN" which is clearly indicated on the Witness page as the mathematical method used to calculate the HBD interest rate.
For those who want a definition of MEDIAN, you can go to https://byjus.com/maths/mean-median-mode/ and see that
median represents the mid-value of the given set of data when arranged in a particular order
So if we have this list: 1 3 4 7 7 8 9
the Median value is the middle value, which is the first 7, so the Median is 7.
I assume this is how the HIVE code calculates the interest rate - by ordering the witness's signaled interest rates from low to high and then picking the middle value.
RE: Signalling for 20% HBD interest