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Why post-purchase surveys catch what last-click attribution misses
Last-click reports credit the final link a customer clicked. Surveys ask what actually made them buy. Here is when each one is right.
Last-click attribution gives all the credit for a sale to the last link the customer clicked before buying. It is easy to measure and often wrong about why someone bought.
What last-click gets wrong
Searches for your brand name. A customer hears about you on a podcast, searches your name a week later and buys. Last-click credits Google search. The podcast gets nothing.
Word of mouth. A friend shows them your product at dinner. There is no link to click, so it never appears in any report.
Video they watched without clicking. People watch a creator’s video, then open your site directly. Many of those visits show up as “direct”.
Privacy changes. Ad blockers, browser tracking limits and app privacy prompts mean pixels see less than they used to. Platform-reported sales are increasingly modelled estimates.
What surveys get right
A survey asks the customer. It catches channels with no link, and it shows up the same way regardless of browser or device. Because the answer is tied to the order, you can see revenue by channel, not just counts.
What surveys get wrong
- Memory is imperfect. People name the most recent or most memorable thing.
- Not everyone answers. You see the customers who answered, which is usually a large share but not all.
- Answers are coarse. “Instagram” doesn’t tell you which ad.
Use both
Treat them as two views of the same customers:
- Use ad platform data to compare ads and audiences within a channel.
- Use survey data to decide how much to spend across channels, and to find channels you aren’t measuring at all.
When the two disagree a lot, for example the survey says 25% of revenue comes from TikTok while TikTok Ads claims 5%, that gap is the most useful number you have. It usually means a channel is doing more than its pixel can show.
A simple weekly check
- Look at survey revenue by channel for the last 30 days.
- Put each channel’s ad spend next to it.
- Compare that return on ad spend with what each platform reports.
- Move a small amount of budget toward channels the survey says are undervalued, and watch the next month.