User Simulation Primer
02Modelling

How the models are built

There are three ways to build a model: prompt it, ground it in one person’s data, or train it, and a provider can combine them. The introduction sorts the names for the category by which of these they describe. Providers also differ on whether each simulated person is a twin of one real person or a simulated individual, and on whether accuracy is scored at the individual level or the audience level.

Prompt a persona

A general-purpose model is told who to be: “You are a 34-year-old nurse in Leeds.”

NamesAI personas, silicon samples

LimitCan match some groups’ answer shares but misses others, and flattens individuals into stereotypes of their group.Argyle et al., 2023; Santurkar et al., 2023; Wang et al., 2025

Ground in a person’s data

A general-purpose model reads one person’s interview or survey answers before it replies as them.

NamesGenerative agents of real people, and the digital twins in Toubia et al. and Peng et al.

LimitAnswers vary less than real people’s and move towards the average on new questions.Peng et al., 2025

Train on people’s records

A model is trained on what real people said and did, usually by fine-tuning a language model.

LimitNeeds large sets of real responses. Some systems train one model across many studies; others train one per audience, which needs data for each.Kolluri et al. (Simile), 2025; Dahiya (Semilattice), 2026

Where each provider sits

Most providers now publish something about their methods. Each is placed by what its own pages and papers say.

A twin of one real person
A simulated individual, not a real person
Trained on data about people
Artificial SocietiesListen LabsSimile
AaruSemilattice
General-purpose language models
None of the providers here
Prompting tools

Not placed: Electric Twin, which does not say whether its models are twins of real people.

Twins of real people

Agents grounded in each person’s own interview reproduced 85% of that person’s retest consistency. Park et al. (Simile), 2024 (v1)

Yes
  • Artificial Societies Each persona grounded in a real individual
  • Listen Labs One model per real interviewee
  • Simile One agent per participant
No
  • Aaru Simulated individuals built from population data
  • Semilattice Each simulated person represents a cluster of similar real people, with only the traits they agree on, mined from their own answers
  • Prompting tools Personas written into a prompt
Not described
  • Electric Twin

Score each simulated person against the real one

Early studies built simulated people from demographics alone and mostly checked answer shares for groups. Argyle et al., 2023; Santurkar et al., 2023

Yes
  • Listen Labs Held-out interview answers
  • Semilattice Each person’s newest records held out
  • Simile Against each person’s own retest
No
  • Aaru Scored on answer shares
  • Artificial Societies Scored on answer shares
  • Electric Twin Scored on answer shares
Not described
  • Prompting tools

Train a model on data about people

General-purpose models are tuned on human feedback to be helpful assistants (RLHF), which reduces the variety of their answers. Kirk et al., 2024

Yes
  • Aaru Its own population model
  • Artificial Societies Rothko, trained further on decisions
  • Listen Labs Each twin trained on the client’s outcomes; method not given
  • Semilattice A fine-tuned adapter per cluster of similar people
  • Simile A fine-tune of Qwen
No
  • Electric Twin General-purpose LLMs constrained by survey data
  • Prompting tools General-purpose LLMs as they ship

Test beyond survey questions

Synthetic answers can match a survey while regression results estimated on them change size or sign. Bisbee et al., 2024

Yes
  • Aaru Brand rankings against card-purchase data
  • Artificial Societies Question-wording experiments and coherence
  • Electric Twin Focus groups and image and video tests
  • Simile Personality tests, economic games and experiments
No
  • Semilattice Survey items only; journeys not yet validated
Not described
  • Listen Labs
  • Prompting tools

Report how confident each result is

Yes
  • Aaru Predicts its own error for each question
  • Listen Labs A confidence score, and abstains without signal
  • Simile A trained model predicts each result’s error
Not described
  • Artificial Societies
  • Electric Twin
  • Semilattice
  • Prompting tools

Simulate a new audience without collecting new data

Yes
  • Aaru Simulates a described audience from census and licensed data
  • Simile Returns answers for a described population
  • Prompting tools Any persona can be written into a prompt
No
  • Listen Labs Needs an interview with each person
  • Semilattice Needs a corpus for each audience
Not described
  • Artificial Societies
  • Electric Twin

From each provider’s own pages and papers, October 2026. “Not described” means they do not say either way.