For those who interested, here is a Bitcoin Strength Index source code. I used it on weekly chart with params (close,28). And only with Bitcoin. And only during bull run. It shows how far price went off the particular moving average during bubble run (i.e. being above BB). Weekly MA 28 is approximately daily ma 200.
The physical meaning of this indicator is to show current bull rally "speed".
study("Bubble Strength Index") bsi(scope,length) => s = sma (scope,length) [mid1,high1,low1] = bb (close,20,2) float result = 0 result:=high > high1 ? high / s : 1 plot(bsi(close,28))
and BTC @ 58 k$, I finally became bearish, target BTC @ 40 k$ :