Comparing BTCUSD Longs and Shorts (amount of long / short positions), e.g. as defined by Bitfinex, one can take a general idea whether most of the market participants are short or long. So, if we draw symbol like this: 100*BITFINEX:BTCUSDLONGS/(BITFINEX:BTCUSDLONGS+BITFINEX:BTCUSDSHORTS) we will get 0% - 100% chart, where 100% would mean 'everybody bought, no sell...