A synthetic customer panel, built once from real Jobs-to-Be-Done research, gave a marketing agency a permanent way to test creative work. Every campaign since has drawn on the same panel instead of restarting the argument from scratch.
A data-focused marketing agency with a national client reach had a recurring problem: clients second-guessed creative work based on personal opinion, leading to endless revisions. Affordable creative testing tools didn't exist at their scale. Rather than solve this project by project, we built a permanent asset: a custom GPT backed by JTBD-based customer personas that the agency could return to on every future campaign, not just this one.
"Clients used personal perspectives to provide feedback, leading to multiple revisions and wasted account hours."
The agency needed a more data-driven approach to creative testing that was both effective and affordable. Traditional testing tools were out of reach at their budget. Without objective data, every creative review became a debate based on taste rather than evidence, and the agency had no way to defend their work.
We selected a pilot brand and worked with the account strategist to understand the brand's customer base. Using this foundation, we built a Jobs-to-Be-Done map for each identified customer archetype: main job, sub-jobs, emotional and functional criteria, and circumstances.
Using the JTBD maps as a foundation, we worked with the LLM to develop two detailed personas per archetype, creating a synthetic panel of nine customers. The panel was grounded in real job structure, not invented demographic profiles.
The panel, persona maps, job maps, and additional guidance were built into a custom GPT the agency could return to on every new campaign, not rebuild for each one. The tool produced a percentage desirability score and customer quotes the agency could present to clients alongside the creative work.
Clients had greater confidence in the future performance of their ads, because the creative work was now backed by data-driven insights from a synthetic customer panel rather than gut feel. The agency experienced a measurable reduction in client-requested revisions and gained a repeatable, affordable process for validating creative work, one they could run again on the next campaign without rebuilding it from scratch.