San Francisco CA
Posts: 2 since Jul 2013
Thanks Given: 0
Thanks Received: 1
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I've used WFO for several months across over 100 strategies (across portfolio of futures, stocks, ETFs) and it's been a frustrating experience. Even strategies with few parameters that perform well (Profit Factor>1.6, APR>20%, MAR>0.5) break down in WFO.
Wanted to share my learnings and generate a discussion around best practices..
1) Objective function really matters - choosing "Highest/Lowest" metrics (e.g. Highest Profit Factor, Highest Select Net Profit, Highest MAR, etc) set you up for failure - by definition, they pick the outliers in-sample period which invariably fail in out-of-sample periods. Ideally an objective function should do well across 3 independent metrics/dimensions through some sort of a ranking function (e.g. 80 percentile ranks in each of these dimensions). The three dimensions are
- measurement of trade performance - e.g. Profit Factor, Trade Efficiency
- measurement of capital utilization - Net Profit, Exposure, Select Net Profit
- measurement of portfolio drawdown risk - e.g. Max Drawdown, Lake ratio, Sortino Ratio, etc.
I haven't come across any tool that offers this kind of objective function. If you have any suggestions please advise.
2) In WFO of portfolios/baskets of symbols, per-symbol strategy parameter values perform much better than average parameters across basket/portfolio. I haven't seen tools that support per-symbol optimized values (not sure of NinjaTrader, but most others don't).
3) WFO time period - while the 3:1 (3 in-sample, 1 out-of-sample period) ratio is well-establish, there are no guidelines of the absolute period of WFO - for a daily strategy, is it every 3 months, 1 year etc. Ideally, this should mirror the regime change period of the symbol. In fact, in absence of a tool that does interval optimization across different time periods to determine best regime period for each symbol and runs WFO over that regime, most WFOs will fail.
I've reached a conclusion that unless you do WFO correctly that accomodate these 3 factors, you will tend to discard robust strategies with good potential and get disillusioned.
-> Wanted to get your sense of success rates with WFO - of all the strategies you've backtested/optimized and felt excited/comfortable, how many have you successfully walked forward? And how? Any pointers from experts would be helpful.
thanks
Kiran
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