The Aggression Factor is a number that tells the optimizer the smallest sized subset of trades to hunt for when it optimizes.

The range of values is from 1 to 49 and is in terms of a percent of the total set of trades in the backtest.

For example, the default value of 33 tells the optimizer to look for sets of trades at least 33% of the total trades in the backtest.

So if there are 1000 trades in your backtest, the smallest set it will find is 333 trades if the aggression factor is set to 33.

If you set the aggression factor to 1, you're allowing the optimizer to look for much smaller sets of trades, e.g. sets of 10 in our backtest with 100

1000 * (1/100) = 10 trades

In general, when you create a new strategy, you should have a large number of trades in the backtest. You can use larger aggression factors to cull lots of poor trades from the strategy.

As the strategy becomes more mature, you'll want to use a smaller aggression factor so you can remove fewer trades from the strategy, preserving total profit.

The maximum value is 49 since you can divide a backtest into two sets of trades each having more than 50 percent of the total trades in them.