I arrived 279 based some calculation (volatility of year 2004 to 2008), as such this no. is playing good role. I am writing options based on this since from 2008 with crisis management strategy.
If you consider 230 or 250, it will fail.
Whenever the premium is below 180 or 190, market movement will be one side or closing will be +/- 60 points settlement to settlement.
Rish