WAS ratio is based on the median, not the average

[mherrmann3]

As described on gridcoin.us/wiki/whitelist-process.html, the WAS is defined as the ratio of the median of the last 7-day and last 40-day credits.

If the credits-per-day are more or less constant, it can indeed be approximated with the average. But as soon as the credits-per-day fluctuate strongly, the average and median will start to differ. Especially if zero-credit days are involved, the median may behave completely different: imagine if 21 days have zero credit. Then, the 40-day-median will be also zero and the WAS ratio undefined (division by zero), i.e.., not > 0.1 (green).¹

Footnotes

1. This special case is somehow a hidden third criteria in the white/graylist definition: a project must have less than 21 zero-credit days to be whitelisted. So if you cannot implement the median, you may at least check for this special case. ↩

[RoboticMind]

Oh oops that's actually an error in the documentation. (I would know, I also wrote the documentation)

The original definition was defined as

WAS = Green If (Mean daily credit for 7 Days > (0.1 * Mean daily credit for 40 Days)) Else Red

gridcoin-community/Gridcoin-Tasks#194

Dividing the two gives you

Mean daily credit for 7 Days / Mean daily credit for 40 Days > 0.1

I did later notice that the original definition does avoid the division by zero issue edge case, however it also fails the ZCD check when that happens so I wasn't too concerned

[RoboticMind]

PR has now been put up to fix the documentation on the gridcoin.us site

gridcoin-community/Gridcoin-Site#426