The short answer
Prospecting and retargeting describe audience strategies, not guarantees of customer identity or incremental value. Retargeting can reach people with prior contact, while prospecting aims to reach a broader potential audience. Compare their roles and measurement rules before comparing headline ROAS.
Check who actually entered each audience
Write down inclusion and exclusion rules, lookback periods, and whether existing customers can be reached. A campaign labeled prospecting may still include people who already know the brand. A retargeted visitor may never have purchased. Use order history for customer classification rather than inferring it from the campaign label.
Compare the same measurement basis
Illustrative inputs: prospecting spends $3,000 and receives $9,000 attributed revenue, or 3×. Retargeting spends $500 and receives $3,000, or 6×. If the two reports claim overlapping orders, the $12,000 sum is not necessarily unique store revenue. Reconcile duplication before presenting a combined result.
Do not infer a budget opportunity from the ratio
The 6× example does not show that retargeting could absorb the entire prospecting budget at the same return. Audience availability, prior intent, repeated exposure, and the stream of new visitors can change with spend. A high average describes the observed activity; it is not a forecast for a larger budget.
Check the economics and the acquisition mix
Look at contribution per order, refunds, new-customer revenue, and acquisition cost. If a prospecting campaign generates customers whose later purchases matter, report that cohort’s realized later value separately. Do not count the same later sale once as a projected prospecting return and again as unique retargeting revenue in a business total.
Use evidence suited to the question
For operational reporting, consistent attribution and deduplicated order totals are useful. For a causal question about added sales, use an appropriate experiment or defensible comparison. Document uncertainty and audience overlap. The goal is to understand how the strategies work together economically, not to force every campaign into an identical headline target regardless of purpose.
Inspect audience overlap
- Gather: Record inclusion, exclusion and lookback rules plus the orders claimed by each group.
- Produce: Deduplicate business totals and compare new customers using actual customer history.
Decision boundary: A campaign label does not prove the identity or incremental value of its buyers.
Next reading
Examples are illustrative, not client results or benchmarks. The calculations use the inputs shown; real-world decisions depend on your records and assumptions. Report a correction.