Ok,
I think I understand what you are referring to now. If you are referring
to the "Charts" page of the backtest report (i.e. from Statistics |
Charts | Trades | Formula | Settings | Symbols), then yes, most of those
charts are measuring changes of equity. The same trade taken over and
over will have a lesser and lesser impact on equity as equity grows.
However, the last chart, "Profit Distribution" is based on individual
trade results, not changes in equity. If you want to compare the
characteristics of trades between backtests, refer to this chart.
Here's a sample code you can backtest (using "current symbol") over an
extended period (e.g. 1/1/06 - 12/31/09):
SetOption("InitialEquity", 100000); // Start with $100,000
SetPositionSize(10000, spsValue); // Bet $10,000 on every trade
SetOption("PriceBoundChecking", false); // Disable valid price check.
SetTradeDelays(0, 0, 0, 0);
Buy = Month() != Ref(Month(), -1);
BuyPrice = Open;
Sell = Month() != Ref(Month(), 1);
SellPrice = ValueWhen(Buy, BuyPrice) * 1.50; // Force every trade as
50% winner
The "Profit Table" chart will show a decreasing return each year since
the fixed performance is less and less relative to the growing equity.
However, the "Profit Distribution" chart will show all trades as as 50%
or 55%. They should actually all be 50%, but I assume that there are
rounding errors causing some to get bumped up into the next category.
If you want to include your own charts in the report, you can add any
AFL file to the directory <AMIBroker Home>\Formulas\Report Charts
For example; You could write your own table chart that displayed the
average trade result for each month rather than the change in equity.
In the example above, every monthly cell in the table would show 50%.
Mike
