Quote from mizhael:
How do you compare the realized performance of the strategy to your expectation, given the future may not be similar to the past at all?
How do you form your expectation in the first place?
And once you decide a strategy is not working, you turn it off, and then when do you turn it back on? Based on your view again?
I have years of backtests with thousands of trades for multiple strategies, so I have a pretty good idea how they perform in a variety of conditions. I do make adjustments and temporarily stop trading some strategies based on basic market timing, not to improve returns but to reduce risk. I am also aware that markets can change and strategies can stop working so I trade multiple strategies and I monitor them. I am always looking for better ideas so generally I stop trading a strategy because I have a better one to take it's place. In the summer of 2008 all my longer term (weeks) long strategies started breaking down early in the summer. My short term trading was holding up so I switched to this entirely. This was entirely subjective, but it was very uncharacteristic to see everything else breaking down. I was slow to get back in to the longer term strategies, but my shorter term strategies are better anyways, so I was in no hurry.