Incrementality Testing: Which Orders Are Truly New?

Attributed orders are not always new business. Use a control, contamination log, and business results before keeping, reducing, or retesting spend.

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12/12 lessons

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Published

2026-04-25

Updated

2026-07-13

Last reviewed

2026-07-21

Review scope Reviewed against Shopify, Google Search, ads, analytics, and ecommerce operating workflows.

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12/12 lessons

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Attributed orders are not always new business. Use a control, contamination log, and business results before keeping, reducing, or retesting spend.

Learn to read CPM, CPC, CTR, CPA, ROAS, and attribution as one decision system, so you can tell whether to fix, pause, or scale spend.

Turn the question into plain language: would orders, new customers, and contribution profit fall without this ad layer? Before reading platform ROAS, name the layer being tested: branded search, remarketing, PMax, audience, or region.
Check order volume, whether regions or audiences can be separated, whether promos, stock, and email cadence are stable, whether the buying cycle is covered, whether tracking is stable, and whether a 10-14 day test is safe enough.
Compare platform revenue with Shopify total orders, new customers, non-paid orders, AOV, refunds, checkout completion, and contribution profit. If platform revenue falls but total orders and profit hold, the layer may be capturing existing demand.

Incrementality Testing: Which Orders Are Truly New?