Quote from Kevin_in_GA:
There is always a now when it comes to placing a trade, but let's avoid philosophical arguments for the moment.
I agree that the half-life needs to be considered when trading pairs, since it helps in managing your trades. PTF gives you and "average days in trade" number which is not the half-life.
I just completed some interesting statistical analyses of cointegration versus correlation on 6 of the 9 S&P sector constituents. Preliminary analysis is posted here.
This is based on 1 year of data (shortest timeframe for backtesting in PTF) and 1 year of trades. Settings were entry at delta > 2, exit at delta < 1, 100 day mean and SD used.
To me, this is a pretty compelling set of data for using cointegration rather than correlation.