RB - Since you asked, some personal information is in my profile...
It is the power of Excel that allows one to accomplish computational tasks that would have been unimaginable before the advent of the PC. You can trash Bill Gates and MSFT all you want, but the value of the MS Office package and Excel in particular is just incredible. The approach we employ is to allow the market data itself to define the values of our various rules and settings, and going forward, to do that relatively frequently so that our composite program algorithm remains as well tuned as possible to how the market is trading most recently (e.g. there was a marked shift in the market's trading behavior with the elimination of the Uptick Rule in July 2007). The ability to see how a change affects the long term and short term results virtually instantaneously is an extremely powerful capability and removes the subjective biases that "recency" introduces. Many seemingly good ideas fall by the wayside for failing to pass muster in the back test. Specifically, given that our MACD/Slope implementation is a viable technique for defining IT Bull/Bear conditions, and for further defining which rules should contribute in those conditions and how much, it is the historical market data itself that defines which EMAs (i.e. 10, 66) and smoothing periods work best.
