I trade only the RUT I use sigma as first choice (>1.2), then I look at R/R (>8%) puts have a higher R/R than calls so I start with the put side 2 months, 3 months ahead. if possible I sell a call spread and accept a lower R/R (5%) I close when 80% of the profitpotential has been reached and when I see possibilities to sell a spread with expiration later or I sell when it gets too close to the short strike.
sigma = std.dev = (short strike - index) / ( index * volatility * SQRT(days to exp. / 365)) I use calendar days (365) although I saw some "guru" use trading days RUT aug put 740 has a sigma of -1.62 (RUT = 840.04 RVX = 21.13)
Thanks for your time and your sample. It was my mistake. I thought that you were talking about selling puts (or calls) when the std.dev of the index was above |1.2| respect to his mean (of "n" days).