Quote from mysticman:
IV_Trader, when you say that Egar shows MO correlation at 17%, what exactly are you referring to as your source for that? Are you an EGAR subscriber?
You have also been doing full replication on the Dow, so why the change? Because of its price weighting, the Dow is not particularly suited to partial replication, although other factors such as beta may come into play.
Yes, there are a lot of factors to consider in dispersion. The first fractor is the time frame of your trade. If it is to be greater than 1 month, then probably volatility would be more important. Thus for regular dispersion the IV should not be high and the IV/HV ratio should be looked at. This would be similar to the criteria for a good straddle.
On the other hand, if your time frame is 1 month or less, then correlation becomes more important than volatility (gamma more important than vega). Then what EGAR calls the "third volatility level coefficient" becomes most important. The main formula is then calculated with price correlations and HV rather than IV and component IV correlations.
Beta is also important as the combination of volatilty and correlation, but it would need to be calculated yourself short term. 5 year betas given out by almost all sources are useless.