DIAG-14 · Diagnosis · Invariant — holds by construction, no expiry

Conversion happens downstream

The law

Click-path conversions are sessions times per-source CVR, summed; ad levers act only through delivered-session volume and composition (including ad-set expectations); site-side changes touch every source; a binding downstream capacity cap zeroes marginal conversions from added traffic.

Scope

Click-attributable, site-visit-mediated outcomes (excludes in-ad lead forms, call ads). A CVR shift alone never localizes cause, ads change visitor composition too.

What this licenses you to do

Before approving any spend increase, verify the funnel converts current traffic and no hard capacity stage binds; read a CVR deficit roughly uniform across independent sources as a shared site-or-market factor, not an ads factor.