When doing a rubustness check using a 12 week hold, should I do a robustness check using all 12 different start dates or just 4?

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at 05/03/11 11:31 PM : RE: how many periods

When doing a robustness test using a 12 week rebalance over a long backtest time span, I'll often use a 12 week robustness test. But if you think about it, 4 weeks is likely fine enough for a quick validation or not because week 5 in the first period of the 12 week robustness test and week 1 of the second period of the 4 week robustness test will essentially recreate the same thing. The difference however will resde in the average return of all runs. For example, if you're averaging 12 runs vs. 4, the results will vary. Not so much because the runs will be different. But if the test was a year long, the last run in a 12 week robustness test will only have 3 quarters of a year of results (and run 11 will be 3 quarters and 1 week's worth of results, and etc.), whereas the 4 weeks will go thru the full year, give or take an extra week or two, thus making the runs within your average of all runs calculation more similar time-wise.

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