I think c) . Just calculate your capital with the square root rule from the manual, then use the backtest for setting the Margin slider so that it matches the capital. From your posts I see that you have understood how to do this. The other formula was just the rule of three for quickly adjusting the Margin slider to a new investment. It was not for updating to a new version. If it causes trouble and confusion then just forget it and set Margin by backtest.

Thanks jcl. We're finally in agreement on a lot of things!!!

I thought the correct answer was c) too.

I agree with not using a formula(s) one doesn't understand - that's why I keep asking...

I also agree with saving backtests - especially now that they take so long, esp. for Z12.

While I understand the method above, it's even more so too cumbersome now given the latest Z12's Test times. Can't the rule of 3 save us?! We don't all have unlimited budgets to run on Tianhe-2, aka Milky Way 2...

So, my (perhaps final ) question is: Can the rule of 3 be applied as follows: Run backtests only once for the new version to find the Margin setting that gives the original, starting CR. Then apply the rule of 3 using that NewVersionOriginalMargin?

In the example above, run backtests to find NewVersionOriginalMargin = Margin on <new> version that gives CR=$1k.

Then, whenever one wants to reinvest (while still on that same version) no backtests needed! Simply rule of 3 calculate NewMargin=(CurrentCapitalPerSquareRootRule/OriginalCapital)*NewVersionOriginalMargin.

This seems to me to apply the rule of 3 as if no earlier versions existed and only the new version had been run since starting. Is there some reason this doesn't work?

Thanks.

Hi jcl. Wondering if you've had time to review the above and if this alternate method works?

Thanks.

This should work. The rule of 3 is valid as long as the linear relationship between the parameters does not change.

Thanks for the confirmation! This is certainly _much_ faster than running Tests every time!

Thanks.