attached now.nothing attached
Thank you! Appreciate your response and I will give this a go.First, MC analysis is very important as it allow you to fully understand how your system performs with selection bias. Second, the way MC is done in AB is pretty poor and rudimentary at best. Best way to do MC analysis is add the code "mtRandom() > 0.7" to your "buy" line. Insert a dummy parameter and optimize it over say 1000 or more runs. Export the optimization output into a CSV file and then import into Excel. Then using the Data Analysis plugin select an output parameter (say net profit or system draw down) and put that into a histogram. What you will then get is a complete picture of how your system performs with selection bias. This is much more insightful than the built in MC of AB. Also the way AB does MC is a little questionable. Here is a few pics of a system I recently back-tested using the same technique. For simplicity I'm only including net profit and system drawdown but you can pretty much review any back-test output stat from AB to get a complete picture of how your system performs with selection bias. Like I said, MC testing is extremely important if you really want to understand the behavior of your system. It is very hard to judge a system's performance based on a single run.
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Without getting too complex, the MC in AB is not simulating any variables. For want of a better description it just does a shuffle of the order in which stocks are taken. In the mtRandom() example I did your simulation will make a binary decision as to whether an entry should be taken so what you get with the dummy optimize is a a bunch of different stock selections if that makes sense.Thank you! Appreciate your response and I will give this a go.
After I get the buy setups, I use position score to rank the stocks. Then i pick the top 10 stocks to start with and as I exit positions, i take the top stock, ranked by the position score, every month.
So, what I am trying to figure out is which variable Monte carlo is trying to simulate? Is it just the timing of which month I start trading my system? I believe picking of the stocks from a bucket of stocks is no longer random due to ranking the stocks.
Regards,
Hari
Thanks Warr87. MDD is fluctuating based on the year I start. The back test report started on Jan 2008. But if I had started on Jan 2007, MDD became -33%. This was due to the outlier year - 2008.if its a rotational monthly system then it hinges on your ranking method. improving that will change the stats.
from whats presented it appears to be a good system, though I'm not sure how you got such a low MDD from 13yrs of backtesting. seems unusually low.
great inputs. Thanks. Yes, I played with the number of positions and 10 is the sweet spot for my system as well. I dont have an index filter, but my exit is tight. I get out on the first sign of weakness. However, due to the system being monthly, first sign of weakness is often too late!start time is definitely a factor. even sharpe ratio (if you like that metric) will drastically change if you happen to backtest right before a 'black swan' event. but that's also why the MDD being less than 20% over such a long period of time seems low. but i don't know what kind of filters you have in place. and it by no knows your results aren't valid.
looking at an average DD could also be important to have a realistic understanding of how often, or to what degree, you are in a DD. MDD is obviously the worst case scenario.
im currently really likely my own monthly momentum system, though mine is 'riskier' than yours (I removed index filters), though my return is higher. it has been trading pretty well right now.
my own system, in my testing, appeared to fair better with more positions as well. something for you to consider. (I currently run it with 10 positions, but even up to 40 positions it has reduced MDD likely due to a spread risk amongst more positions.)
I now have these for my system. Troubling part is the net profit that I get when I run the system for the same time frame(as the optimization) is not even reported in the optimization reports!First, MC analysis is very important as it allow you to fully understand how your system performs with selection bias. Second, the way MC is done in AB is pretty poor and rudimentary at best. Best way to do MC analysis is add the code "mtRandom() > 0.7" to your "buy" line. Insert a dummy parameter and optimize it over say 1000 or more runs. Export the optimization output into a CSV file and then import into Excel. Then using the Data Analysis plugin select an output parameter (say net profit or system draw down) and put that into a histogram. What you will then get is a complete picture of how your system performs with selection bias. This is much more insightful than the built in MC of AB. Also the way AB does MC is a little questionable. Here is a few pics of a system I recently back-tested using the same technique. For simplicity I'm only including net profit and system drawdown but you can pretty much review any back-test output stat from AB to get a complete picture of how your system performs with selection bias. Like I said, MC testing is extremely important if you really want to understand the behavior of your system. It is very hard to judge a system's performance based on a single run.
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I now have these for my system. Troubling part is the net profit that I get when I run the system for the same time frame(as the optimization) is not even reported in the optimization reports!
If I am interpreting the net profit % graph correctly, does that say that the system is more likely to generate profit between 382% and 800%?
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Number of trades are about 350 over 13 years, that is up to 2 trades on an average per month, with 10 open positions most of the time.BTW, how many trades did your system do in that 13 year period? The other reason I was reluctant to go live with my monthly system is I felt the number of trades wasn't statistically relevant so my level of confidence in the back testing was low
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