You asked about which Hist Volatility 2 use.... well if you want to be true to the analysis then you probably need to have it over a year....
But thats a bit of a pain (but you don't want it to come back and you in the bum).
I would have a couple of Vols available and calculate the Probability of them all.
Infact the way I run my live spread sheet (uses a Marketcast feed), is to calculate a Anytime Probability on the bid price, the last price and the margin price (so I'm essentially looking at various Ivols, and comparing them with a hist vol (I use a an average of the exponential 10,20,50, and 1 year, but what the hell, not sure it matters a lot anymore as the Ivols are what you have to trade against).
I do this realtime using the next 6 months options info on selected stocks. I have a filter than runs through the lot and flashes at me when something is within my range of probability/#option/price for writing.
Tends to be quite processor intensive though!
So which one do you use as a Hist Vol. Well thats a personal thing although some tend to go for the 20 day.
