Quote from nitro:
The reality is that markets trade often 1 to 1.5 standard deviation from where they should. That equates to about $1 to $1.5 Trillion dollars. So if your FV models says 1542, add 1.5 standard deviation and keep size small and hit hard at 1.5 stddev from FV. Size should go up at 3 std, and it should be max size at > 5 stddev. Crashes can wipe you out on the downside [the crash of 1987 was a 20 stdev event!!! The Flash Crash was a 10 stddev event] so have to skew downside risk.
That is the lesson I have learned over 30 years. Trade small size all you want, wait to hit hard or accumulate a decent position only at substantial stddev from FV.
So many people make calls. The calls should be stated in relation to the position size they are taking. That tells you their actual conviction. People tend to size based on volatility but that is only half the right equation imo.