Does a fifteen-year pattern in the dollar survive a second data source?
Two blind spots in backtest validation
- Problem
- A strategy on the U.S. Dollar Index showed a 15-year overnight pattern, and standard overfitting tests rated it robust. Before anyone puts money on a result like that, someone has to find out whether it’s real.
- What I did
- Rebuilt the test on independently sourced data: ICE Dollar Index futures and five CME currency futures from Barchart, plus Federal Reserve spot and interest rates from FRED. Rebuilt the spot index from its six currencies with ICE’s formula. Wrote a one-line screen that flags bad opening prices, and a search engine that reproduces the original backtest exactly on all 1,312 configurations, about 17× faster, so the whole search could be rerun 2,000 times against luck. Research assistantship with Prof. Eugene Pinsky.
- Tools
- Python (pandas, NumPy, statsmodels), Excel for the first pass, SQL for the published dashboard. Newey-West, White’s Reality Check, Hansen’s SPA, CSCV.
- Result
- The pattern lived only in the free feed’s opening prices: −1.36 there, +0.25 on futures and +0.22 on the rebuilt spot index. Published as first author in Risks (October 2026). The same screen flagged 10 faulty series out of 37 price feeds before they reached any analysis.