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Backtesting & Statistics

How to Write Down a Test First

Writing a test down first means filling in the rule, the bars, the costs and the pass line on a dated card before a single bar is looked at, so the bars can write only the result. This paper shows you the card in five lines; the idea as a called shot on a billiard table; the card for the plain 10:00 to 18:00 rule on the euro as it was written on 1 March 2026, whose result came back minus 52.2 after costs and under the line; the four after-the-fact edits that would have passed it and why none counts; and the Inputs tab of the Strategy Tester on your platform, saved to a dated file before Start.

Difficulty
Advanced
Reading time
5 min
Pages
8
Reviewed by
Saman Rahbar

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The test card, in five lines

Writing a test down first means the card has five lines and four of them are filled in before a single bar is looked at: the rule, the bars it will be run on, the costs that will be taken off, and the pass line, which is the number the result has to clear or the rule is dropped. The bars are allowed to write only the fifth line. For the example rule on the euro, buy at the 10:00 open and sell at the 18:00 open on every weekday from 2 March to 4 September 2026 with 1.5 pips off each trade, where a pip is the fourth decimal place of the price, the fifth line came back plus 150.3 before costs and minus 52.2 after them. That is under the line, so the rule is dropped, and the card is what stops the writer from arguing.

Calling the pocket

Picture a billiard table with the top right pocket ringed before the cue has moved: the shot is called. A ball that drops into any pocket is luck; a ball that drops into the named pocket is the shot, and the difference is only that the pocket was named first. A test written down first is a called shot. The pass line is the pocket, and it is named out loud, on the card, before the bars are run, so that afterwards there is no picking whichever pocket the ball happened to fall in.

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