Open interest explained
Open interest is the total value of futures contracts that are still open. Rising open interest with rising price shows new money entering long positions; rising open interest with falling price often means new shorts.
Long/short ratio
The long/short ratio compares accounts holding long positions with accounts holding shorts. A ratio of 1.5 means 60% of accounts are long. Extreme readings combined with fast open-interest growth have often come before liquidation cascades.