A post-purchase survey is a single-question form shown on the order confirmation screen the moment checkout completes — most commonly “How did you hear about us?” with a fixed list of channel options (Instagram, TikTok, YouTube, podcast, friend, search, TV, etc.) and an open-text “other.” The data it produces is zero-party: customer-declared at the moment of purchase, not inferred from a click chain or a pixel fire. Multi-question variants exist for NPS or repeat-purchase reasons, but the attribution use case is the HDYHAU question.
Operators read the output three ways. The first is channel-mix percentage by cohort — what share of new customers in this month or this campaign window named each channel. The second is a “discovery channel” attribution view that sits alongside platform-reported and modeled attribution rather than replacing them. The third is slicing the self-reported channel by AOV or first-order LTV to see which sources bring higher-value customers — a podcast cohort that converts at a higher AOV than the Meta cohort changes how the budget conversation goes. Fairing (formerly EnquireLabs) and KnoCommerce are the Shopify-native vendors that made this layer standard in the DTC stack.
The reason it gained traction is structural. Post-ATT, click-based attribution under-counts upper-funnel and word-of-mouth channels — podcast, influencer, connected TV, organic social, friend referral — because no click ID ever lands in the conversion event. The platform sees a direct or branded-search session and credits accordingly. A post-purchase survey surfaces those channels because the customer names them directly, which is the single thing click-based attribution structurally cannot do.
The caveats are real. Customers carry recall bias and over-attribute to recent or memorable touchpoints; paid search is chronically under-reported as “I just Googled it” or folded into brand recognition; response rate is sensitive to placement and drops sharply when the survey moves off the confirmation page; and there’s a gap between the discovery channel (where the customer first heard of the brand) and the decision-trigger channel (what closed the purchase). Read the output as one input in a triangulated stack — alongside platform attribution, incrementality testing, and geo lift — not as a replacement for any of them.