<b>Myth: kill the lowest-attributed channel and reallocate its budget for free upside</b>

<b>Myth: kill the lowest-attributed channel and reallocate its budget for free upside</b>

The question: your attribution report ranks channels by credited conversions; the bottom one looks like dead weight. Cut it, move the money up the list, and gain efficiency — sound logic?

Why it backfires: attributed credit measures observed last-mile (or model-weighted) presence, not marginal causal contribution. A low-credited channel is often an <i>upper-funnel</i> one whose effect shows up later, under a different touch that grabbed the credit. Cutting it can collapse demand that the high-credited channels were merely <i>harvesting</i>. Several documented cases of pausing 'low-value' prospecting or upper-funnel video saw the supposedly-strong brand and retargeting channels fall too — because there was less demand for them to capture. The credit moved; the conversions didn't.

The nuance: this is the harvesting-versus-generating distinction. Attribution conflates the two — it credits whoever stood closest to the conversion, which is usually the harvester. Reallocating from generators to harvesters can look efficient for a few weeks and then erode the funnel that fed everything. The interaction is exactly what observational credit-splitting cannot see.

Bottom line for practitioners: before cutting any channel on attribution alone, run a real holdout on it (pause in matched geos and watch <i>total</i> conversions, not just its own attributed ones). If total conversions hold, it was harvestable and you can trim. If total conversions drop even though its attributed credit was low, you just found a generator — and the model was lying to you about it.

—
Продолжение про marketing mix modeling — @measurement_brand_aff