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Method

Synthetic panels: methodology questions and answers

Updated 1 September 2026, from our recurring review of published evidence on synthetic sample

How Pervasive Insights™, by City Research Solutions, creates, calibrates and validates synthetic research panels, and what the published evidence through 2026 says about doing it honestly. Every two weeks we review new papers, industry guidance and published objections to synthetic data, and add answers here for the questions they raise.

Two kinds of synthetic sample: Type 1 and Type 2

Not all synthetic respondents are the same. Type 2 synthetic sample is generated from a model's general priors: the system answers as it imagines a demographic would, based on whatever its training data contained. Type 1 synthetic sample is grounded in a specific human dataset: real primary research from the population being studied, with the synthetic layer calibrated against it and validated on held-out human responses. The published evidence through 2026 is consistent that Type 2 approaches flatten variance, lean too hard on demographics, and inflate differences between segments by two to four times, while grounded, calibrated approaches track human benchmarks far more closely. City Research builds Type 1 synthetic panels only: every panel is calibrated against that client's own primary research using a two-pass probability-gate method, and every deliverable reports how well the calibration held.

How do you stop synthetic respondents exaggerating differences between segments?

Published benchmarks in 2026 show that uncalibrated AI respondents inflate the gaps between customer segments by two to four times, which can point a team at the wrong target segment entirely. Our second pass gates each synthetic response through a probability model fitted to the client's own primary data, pulling segment gaps toward what that client's real respondents actually showed. We report a segment-gap ratio (the synthetic gap divided by the human gap, measured on held-out human data) so the client can see how close to reality the panel runs.

How much of our own data do you need?

Less than most buyers expect. Published research shows that a human pilot of roughly five percent of a full sample is enough to align a simulator on the structure of the data, meaning the relationships between measures. We calibrate on primary research the client already has, such as an existing tracker or usage and attitude study, and we set a minimum human cell size per subgroup before we will report that subgroup synthetically.

What fidelity do you report, and at what level?

Three levels. Marginal fidelity asks whether the synthetic response distributions match human ones. Structural fidelity asks whether the relationships between measures match. Individual fidelity, where a matched human sample exists, asks whether each synthetic respondent tracks a real counterpart. We report all three overall and by key subgroup, because published work shows calibration can look strong overall while failing badly for a specific group.

Do you train a shared model on our data?

No. Calibration is per client and per study. Your primary research never feeds a model that serves any other client, and nothing you share with us improves anyone else's panel. This is a deliberate design choice: the alternative, a single model trained on a pooled bank of past studies, cannot be tuned to your market, your categories, or your respondents.

How stable are results between runs?

Synthetic estimates that change every time you run them are not research. We fix the generation settings, run replicates, and publish a tolerance band alongside every synthetic estimate, so you know both the number and how much it moves. Run-to-run instability is one of the main published criticisms of synthetic sample, and it is answerable with engineering discipline rather than promises.

How do you avoid the flat, over-agreeable answers AI is known for?

Two mechanisms. First, responses are generated as text and then mapped to scale points, a technique shown in 2026 research to restore realistic response spread that direct numeric prompting collapses. Second, the probability gate corrects directional bias, which the published evidence shows text mapping alone does not fix. The combination addresses both known failure modes: too little variance and too much agreement.

How is synthetic content labelled in your deliverables?

Every table, chart and export carries a tag identifying it as synthetic or human, consistent with the transparency requirements of the ICC/ESOMAR International Code. The method note on every deliverable states the calibration source and its date. A client should never have to ask whether a number came from real respondents.

See it on your own data

Pervasive Insights™ builds this on the research you already own. Tell us what you have and the questions you wrestle with, and we will show you your portal in operation.

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