When people search more for a topic than they did over recent weeks, the model goes short the index for the following week; when they search less, it goes long. This is the strategy from Preis, Moat & Stanley (2013), extended to topics as in Curme et al. (2014).
The shaded band is where 95% of random weekly long/short strategies would finish on the same weeks. A strategy that stays inside the band is indistinguishable from coin flips.
Search volume versus its trailing Δt-week average. Above zero means a short call for the following week; below zero means long.
Strategy return over the trailing 52 trades. The article notes the relationship weakened after 2012; this shows whether that holds for your setting.
Full-period z-score for each topic basket at each Δt. A real effect should hold across neighbouring windows, not appear at one Δt only. |z| ≥ 1.96 is significant at 5%.
Picking the best performer after the fact is the classic trap with this kind of data. Ranked by return before the split, then judged on what happened after it. Select a row to load it.
Each Monday the app records the call for every topic basket at Δt = 3 on the Dow and never changes it afterwards. Unlike the backtests above, this is a record of calls made before the outcome was known.
Weeks where volume exactly equals its trailing average are skipped. On the original data, the single word “debt” at Δt = 3 returns +298% with this rule; the paper reports +326%, which falls inside the +282% to +338% range produced by the different ways those tie weeks can be broken.