<b>Why is the attribution window the most consequential decision nobody debates?</b>

<b>Why is the attribution window the most consequential decision nobody debates?</b>

The question: every attribution system has a lookback window — 7 days, 30, 90 — defining how far back a touch can claim credit. It's usually set once and forgotten. Yet it silently determines which channels win.

What the data shows: window length is not a neutral technical setting; it's a thumb on the scale. Lengthen the window and you mechanically shift credit toward <i>early, upper-funnel</i> touches that would otherwise fall outside the lookback. Shorten it and you concentrate credit on closers. Studies of path-length distributions find that for considered purchases, a meaningful share of influential first-touches sit beyond a 30-day window entirely — so a 30-day setting structurally undercounts top-of-funnel by construction.

The deeper issue: the 'right' window is a function of your actual purchase cycle, which you can measure — the distribution of time-from-first-touch-to-conversion. Most teams instead inherit the platform default and never check whether it matches their funnel. A 7-day window on a 60-day B2B cycle isn't aggressive, it's broken.

The nuance: longer isn't simply better. Wide windows inflate spurious credit by absorbing coincidental touches — the same over-crediting problem as long view-through windows.

What to actually do: plot your time-to-conversion distribution and set the window to capture the bulk of it (say, the 90th percentile), not a round number someone picked. Re-examine it when your funnel changes.

<b>Bottom line for practitioners:</b> the attribution window is a hidden weighting parameter. Choosing it by default is choosing your conclusions by default.